Merge pull request #358 from goodboy/switch_to_pdbp

Switch to `pdbp` 🏄🏼

.github/workflows/ci.yml

@@ -26,7 +26,7 @@ jobs:
         run: pip install -U . --upgrade-strategy eager -r requirements-test.txt
 
       - name: Run MyPy check
-        run: mypy tractor/ --ignore-missing-imports
+        run: mypy tractor/ --ignore-missing-imports --show-traceback
 
   # test that we can generate a software distribution and install it
   # thus avoid missing file issues after packaging.
@@ -60,7 +60,11 @@ jobs:
       matrix:
         os: [ubuntu-latest]
         python: ['3.10']
-        spawn_backend: ['trio', 'mp']
+        spawn_backend: [
+          'trio',
+          'mp_spawn',
+          'mp_forkserver',
+        ]
 
     steps:
 
@@ -79,7 +83,7 @@ jobs:
         run: pip list
 
       - name: Run tests
-        run: pytest tests/ --spawn-backend=${{ matrix.spawn_backend }}
+        run: pytest tests/ --spawn-backend=${{ matrix.spawn_backend }} -rsx
 
   # We skip 3.10 on windows for now due to not having any collabs to
   # debug the CI failures. Anyone wanting to hack and solve them is very

docs/README.rst

@@ -6,8 +6,14 @@
 ``tractor`` is a `structured concurrent`_, multi-processing_ runtime
 built on trio_.
 
-Fundamentally ``tractor`` gives you parallelism via ``trio``-"*actors*":
-our nurseries_ let you spawn new Python processes which each run a ``trio``
+Fundamentally, ``tractor`` gives you parallelism via
+``trio``-"*actors*": independent Python processes (aka
+non-shared-memory threads) which maintain structured
+concurrency (SC) *end-to-end* inside a *supervision tree*.
+
+Cross-process (and thus cross-host) SC is accomplished through the
+combined use of our "actor nurseries_" and an "SC-transitive IPC
+protocol" constructed on top of multiple Pythons each running a ``trio``
 scheduled runtime - a call to ``trio.run()``.
 
 We believe the system adheres to the `3 axioms`_ of an "`actor model`_"
@@ -23,7 +29,8 @@ Features
 - **It's just** a ``trio`` API
 - *Infinitely nesteable* process trees
 - Builtin IPC streaming APIs with task fan-out broadcasting
-- A (first ever?) "native" multi-core debugger UX for Python using `pdb++`_
+- A "native" multi-core debugger REPL using `pdbp`_ (a fork & fix of
+  `pdb++`_ thanks to @mdmintz!)
 - Support for a swappable, OS specific, process spawning layer
 - A modular transport stack, allowing for custom serialization (eg. with
   `msgspec`_), communications protocols, and environment specific IPC
@@ -149,7 +156,7 @@ it **is a bug**.
 
 "Native" multi-process debugging
 --------------------------------
-Using the magic of `pdb++`_ and our internal IPC, we've
+Using the magic of `pdbp`_ and our internal IPC, we've
 been able to create a native feeling debugging experience for
 any (sub-)process in your ``tractor`` tree.
 
@@ -597,6 +604,7 @@ channel`_!
 .. _adherance to: https://www.youtube.com/watch?v=7erJ1DV_Tlo&t=1821s
 .. _trio gitter channel: https://gitter.im/python-trio/general
 .. _matrix channel: https://matrix.to/#/!tractor:matrix.org
+.. _pdbp: https://github.com/mdmintz/pdbp
 .. _pdb++: https://github.com/pdbpp/pdbpp
 .. _guest mode: https://trio.readthedocs.io/en/stable/reference-lowlevel.html?highlight=guest%20mode#using-guest-mode-to-run-trio-on-top-of-other-event-loops
 .. _messages: https://en.wikipedia.org/wiki/Message_passing

examples/advanced_faults/ipc_failure_during_stream.py

@@ -0,0 +1,151 @@
+'''
+Complex edge case where during real-time streaming the IPC tranport
+channels are wiped out (purposely in this example though it could have
+been an outage) and we want to ensure that despite being in debug mode
+(or not) the user can sent SIGINT once they notice the hang and the
+actor tree will eventually be cancelled without leaving any zombies.
+
+'''
+import trio
+from tractor import (
+    open_nursery,
+    context,
+    Context,
+    MsgStream,
+)
+
+
+async def break_channel_silently_then_error(
+    stream: MsgStream,
+):
+    async for msg in stream:
+        await stream.send(msg)
+
+        # XXX: close the channel right after an error is raised
+        # purposely breaking the IPC transport to make sure the parent
+        # doesn't get stuck in debug or hang on the connection join.
+        # this more or less simulates an infinite msg-receive hang on
+        # the other end.
+        await stream._ctx.chan.send(None)
+        assert 0
+
+
+async def close_stream_and_error(
+    stream: MsgStream,
+):
+    async for msg in stream:
+        await stream.send(msg)
+
+        # wipe out channel right before raising
+        await stream._ctx.chan.send(None)
+        await stream.aclose()
+        assert 0
+
+
+@context
+async def recv_and_spawn_net_killers(
+
+    ctx: Context,
+    break_ipc_after: bool | int = False,
+
+) -> None:
+    '''
+    Receive stream msgs and spawn some IPC killers mid-stream.
+
+    '''
+    await ctx.started()
+    async with (
+        ctx.open_stream() as stream,
+        trio.open_nursery() as n,
+    ):
+        async for i in stream:
+            print(f'child echoing {i}')
+            await stream.send(i)
+            if (
+                break_ipc_after
+                and i > break_ipc_after
+            ):
+                '#################################\n'
+                'Simulating child-side IPC BREAK!\n'
+                '#################################'
+                n.start_soon(break_channel_silently_then_error, stream)
+                n.start_soon(close_stream_and_error, stream)
+
+
+async def main(
+    debug_mode: bool = False,
+    start_method: str = 'trio',
+
+    # by default we break the parent IPC first (if configured to break
+    # at all), but this can be changed so the child does first (even if
+    # both are set to break).
+    break_parent_ipc_after: int | bool = False,
+    break_child_ipc_after: int | bool = False,
+
+) -> None:
+
+    async with (
+        open_nursery(
+            start_method=start_method,
+
+            # NOTE: even debugger is used we shouldn't get
+            # a hang since it never engages due to broken IPC
+            debug_mode=debug_mode,
+            loglevel='warning',
+
+        ) as an,
+    ):
+        portal = await an.start_actor(
+            'chitty_hijo',
+            enable_modules=[__name__],
+        )
+
+        async with portal.open_context(
+            recv_and_spawn_net_killers,
+            break_ipc_after=break_child_ipc_after,
+
+        ) as (ctx, sent):
+            async with ctx.open_stream() as stream:
+                for i in range(1000):
+
+                    if (
+                        break_parent_ipc_after
+                        and i > break_parent_ipc_after
+                    ):
+                        print(
+                            '#################################\n'
+                            'Simulating parent-side IPC BREAK!\n'
+                            '#################################'
+                        )
+                        await stream._ctx.chan.send(None)
+
+                    # it actually breaks right here in the
+                    # mp_spawn/forkserver backends and thus the zombie
+                    # reaper never even kicks in?
+                    print(f'parent sending {i}')
+                    await stream.send(i)
+
+                    with trio.move_on_after(2) as cs:
+
+                        # NOTE: in the parent side IPC failure case this
+                        # will raise an ``EndOfChannel`` after the child
+                        # is killed and sends a stop msg back to it's
+                        # caller/this-parent.
+                        rx = await stream.receive()
+
+                        print(f"I'm a happy user and echoed to me is {rx}")
+
+                    if cs.cancelled_caught:
+                        # pretend to be a user seeing no streaming action
+                        # thinking it's a hang, and then hitting ctl-c..
+                        print("YOO i'm a user anddd thingz hangin..")
+
+                print(
+                    "YOO i'm mad send side dun but thingz hangin..\n"
+                    'MASHING CTlR-C Ctl-c..'
+                )
+                raise KeyboardInterrupt
+
+
+if __name__ == '__main__':
+    trio.run(main)

examples/debugging/multi_daemon_subactors.py

@@ -27,6 +27,17 @@ async def main():
 
         # retreive results
         async with p0.open_stream_from(breakpoint_forever) as stream:
+
+            # triggers the first name error
+            try:
+                await p1.run(name_error)
+            except tractor.RemoteActorError as rae:
+                assert rae.type is NameError
+
+            async for i in stream:
+
+                # a second time try the failing subactor and this tie
+                # let error propagate up to the parent/nursery.
                 await p1.run(name_error)
 
 

examples/debugging/multi_nested_subactors_error_up_through_nurseries.py

@@ -12,18 +12,31 @@ async def breakpoint_forever():
     while True:
         await tractor.breakpoint()
 
+        # NOTE: if the test never sent 'q'/'quit' commands
+        # on the pdb repl, without this checkpoint line the
+        # repl would spin in this actor forever.
+        # await trio.sleep(0)
+
 
 async def spawn_until(depth=0):
     """"A nested nursery that triggers another ``NameError``.
     """
     async with tractor.open_nursery() as n:
         if depth < 1:
-            # await n.run_in_actor('breakpoint_forever', breakpoint_forever)
-            await n.run_in_actor(
+
+            await n.run_in_actor(breakpoint_forever)
+
+            p = await n.run_in_actor(
                 name_error,
                 name='name_error'
             )
+            await trio.sleep(0.5)
+            # rx and propagate error from child
+            await p.result()
+
         else:
+            # recusrive call to spawn another process branching layer of
+            # the tree
             depth -= 1
             await n.run_in_actor(
                 spawn_until,
@@ -53,6 +66,7 @@ async def main():
     """
     async with tractor.open_nursery(
         debug_mode=True,
+        # loglevel='cancel',
     ) as n:
 
         # spawn both actors
@@ -67,8 +81,16 @@ async def main():
             name='spawner1',
         )
 
+        # TODO: test this case as well where the parent don't see
+        # the sub-actor errors by default and instead expect a user
+        # ctrl-c to kill the root.
+        with trio.move_on_after(3):
+            await trio.sleep_forever()
+
         # gah still an issue here.
         await portal.result()
+
+        # should never get here
         await portal1.result()
 
 

examples/debugging/restore_builtin_breakpoint.py

@@ -0,0 +1,24 @@
+import os
+import sys
+
+import trio
+import tractor
+
+
+async def main() -> None:
+    async with tractor.open_nursery(debug_mode=True) as an:
+
+        assert os.environ['PYTHONBREAKPOINT'] == 'tractor._debug._set_trace'
+
+        # TODO: an assert that verifies the hook has indeed been, hooked
+        # XD
+        assert sys.breakpointhook is not tractor._debug._set_trace
+
+        breakpoint()
+
+    # TODO: an assert that verifies the hook is unhooked..
+    assert sys.breakpointhook
+    breakpoint()
+
+if __name__ == '__main__':
+    trio.run(main)

nooz/329.trivial.rst

@@ -1,7 +0,0 @@
-Add ``key: Callable[..., Hashable]`` support to ``.trionics.maybe_open_context()``
-
-Gives users finer grained control over cache hit behaviour using
-a callable which receives the input ``kwargs: dict``. Further this patch
-avoids use of the internal ``Actor._service_n`` for spawning the
-entering manager tasks and instead allocates and uses an actor global
-singleton ``_Cache.service_n``.

nooz/333.feature.rst

@@ -0,0 +1,25 @@
+Add support for ``trio >= 0.22`` and support for the new Python 3.11
+``[Base]ExceptionGroup`` from `pep 654`_ via the backported
+`exceptiongroup`_ package and some final fixes to the debug mode
+subsystem.
+
+This port ended up driving some (hopefully) final fixes to our debugger
+subsystem including the solution to all lingering stdstreams locking
+race-conditions and deadlock scenarios. This includes extending the
+debugger tests suite as well as cancellation and ``asyncio`` mode cases.
+Some of the notable details:
+
+- always reverting to the ``trio`` SIGINT handler when leaving debug
+  mode.
+- bypassing child attempts to acquire the debug lock when detected
+  to be amdist actor-runtime-cancellation.
+- allowing the root actor to cancel local but IPC-stale subactor
+  requests-tasks for the debug lock when in a "no IPC peers" state.
+
+Further we refined our ``ActorNursery`` semantics to be more similar to
+``trio`` in the sense that parent task errors are always packed into the
+actor-nursery emitted exception group and adjusted all tests and
+examples accordingly.
+
+.. _pep 654: https://peps.python.org/pep-0654/#handling-exception-groups
+.. _exceptiongroup: https://github.com/python-trio/exceptiongroup

nooz/335.trivial.rst

@@ -0,0 +1,5 @@
+Establish an explicit "backend spawning" method table; use it from CI
+
+More clearly lays out the current set of (3) backends: ``['trio',
+'mp_spawn', 'mp_forkserver']`` and adjusts the ``._spawn.py`` internals
+as well as the test suite to accommodate.

nooz/336.trivial.rst

@@ -0,0 +1,4 @@
+Add ``key: Callable[..., Hashable]`` support to ``.trionics.maybe_open_context()``
+
+Gives users finer grained control over cache hit behaviour using
+a callable which receives the input ``kwargs: dict``.

nooz/337.feature.rst

@@ -0,0 +1,41 @@
+Add support for debug-lock blocking using a ``._debug.Lock._blocked:
+set[tuple]`` and add ids when no-more IPC connections with the
+root actor are detected.
+
+This is an enhancement which (mostly) solves a lingering debugger
+locking race case we needed to handle:
+
+- child crashes acquires TTY lock in root and attaches to ``pdb``
+- child IPC goes down such that all channels to the root are broken
+  / non-functional.
+- root is stuck thinking the child is still in debug even though it
+  can't be contacted and the child actor machinery hasn't been
+  cancelled by its parent.
+- root get's stuck in deadlock with child since it won't send a cancel
+  request until the child is finished debugging (to avoid clobbering
+  a child that is actually using the debugger), but the child can't
+  unlock the debugger bc IPC is down and it can't contact the root.
+
+To avoid this scenario add debug lock blocking list via
+`._debug.Lock._blocked: set[tuple]` which holds actor uids for any actor
+that is detected by the root as having no transport channel connections
+(of which at least one should exist if this sub-actor at some point
+acquired the debug lock). The root consequently checks this list for any
+actor that tries to (re)acquire the lock and blocks with
+a ``ContextCancelled``. Further, when a debug condition is tested in
+``._runtime._invoke``, the context's ``._enter_debugger_on_cancel`` is
+set to `False` if the actor was put on the block list then all
+post-mortem / crash handling will be bypassed for that task.
+
+In theory this approach to block list management may cause problems
+where some nested child actor acquires and releases the lock multiple
+times and it gets stuck on the block list after the first use? If this
+turns out to be an issue we can try changing the strat so blocks are
+only added when the root has zero IPC peers left?
+
+Further, this adds a root-locking-task side cancel scope,
+``Lock._root_local_task_cs_in_debug``, which can be ``.cancel()``-ed by the root
+runtime when a stale lock is detected during the IPC channel testing.
+However, right now we're NOT using this since it seems to cause test
+failures likely due to causing pre-mature cancellation and maybe needs
+a bit more experimenting?

nooz/343.trivial.rst

@@ -0,0 +1,19 @@
+Rework our ``.trionics.BroadcastReceiver`` internals to avoid method
+recursion and approach a design and interface closer to ``trio``'s
+``MemoryReceiveChannel``.
+
+The details of the internal changes include:
+
+- implementing a ``BroadcastReceiver.receive_nowait()`` and using it
+  within the async ``.receive()`` thus avoiding recursion from
+  ``.receive()``.
+- failing over to an internal ``._receive_from_underlying()`` when the
+  ``_nowait()`` call raises ``trio.WouldBlock``
+- adding ``BroadcastState.statistics()`` for debugging and testing both
+  internals and by users.
+- add an internal ``BroadcastReceiver._raise_on_lag: bool`` which can be
+  set to avoid ``Lagged`` raising for possible use cases where a user
+  wants to choose between a [cheap or nasty
+  pattern](https://zguide.zeromq.org/docs/chapter7/#The-Cheap-or-Nasty-Pattern)
+  the the particular stream (we use this in ``piker``'s dark clearing
+  engine to avoid fast feeds breaking during HFT periods).

nooz/344.bugfix.rst

@@ -0,0 +1,11 @@
+Always ``list``-cast the ``mngrs`` input to
+``.trionics.gather_contexts()`` and ensure its size otherwise raise
+a ``ValueError``.
+
+Turns out that trying to pass an inline-style generator comprehension
+doesn't seem to work inside the ``async with`` expression? Further, in
+such a case we can get a hang waiting on the all-entered event
+completion when the internal mngrs iteration is a noop. Instead we
+always greedily check a size and error on empty input; the lazy
+iteration of a generator input is not beneficial anyway since we're
+entering all manager instances in concurrent tasks.

nooz/346.bugfix.rst

@@ -0,0 +1,15 @@
+Fixes to ensure IPC (channel) breakage doesn't result in hung actor
+trees; the zombie reaping and general supervision machinery will always
+clean up and terminate.
+
+This includes not only the (mostly minor) fixes to solve these cases but
+also a new extensive test suite in `test_advanced_faults.py` with an
+accompanying highly configurable example module-script in
+`examples/advanced_faults/ipc_failure_during_stream.py`. Tests ensure we
+never get hang or zombies despite operating in debug mode and attempt to
+simulate all possible IPC transport failure cases for a local-host actor
+tree.
+
+Further we simplify `Context.open_stream.__aexit__()` to just call
+`MsgStream.aclose()` directly more or less avoiding a pure duplicate
+code path.

nooz/349.trivial.rst

@@ -0,0 +1,10 @@
+Always redraw the `pdbpp` prompt on `SIGINT` during REPL use.
+
+There was recent changes todo with Python 3.10 that required us to pin
+to a specific commit in `pdbpp` which have recently been fixed minus
+this last issue with `SIGINT` shielding: not clobbering or not
+showing the `(Pdb++)` prompt on ctlr-c by the user. This repairs all
+that by firstly removing the standard KBI intercepting of the std lib's
+`pdb.Pdb._cmdloop()` as well as ensuring that only the actor with REPL
+control ever reports `SIGINT` handler log msgs and prompt redraws. With
+this we move back to using pypi `pdbpp` release.

nooz/356.trivial.rst

@@ -0,0 +1,7 @@
+Drop `trio.Process.aclose()` usage, copy into our spawning code.
+
+The details are laid out in https://github.com/goodboy/tractor/issues/330.
+`trio` changed is process running quite some time ago, this just copies
+out the small bit we needed (from the old `.aclose()`) for hard kills
+where a soft runtime cancel request fails and our "zombie killer"
+implementation kicks in.

nooz/358.feature.rst

@@ -0,0 +1,15 @@
+Switch to using the fork & fix of `pdb++`, `pdbp`:
+https://github.com/mdmintz/pdbp
+
+Allows us to sidestep a variety of issues that aren't being maintained
+in the upstream project thanks to the hard work of @mdmintz!
+
+We also include some default settings adjustments as per recent
+development on the fork:
+
+- sticky mode is still turned on by default but now activates when
+  a using the `ll` repl command.
+- turn off line truncation by default to avoid inter-line gaps when
+  resizing the terimnal during use.
+- when using the backtrace cmd either by `w` or `bt`, the config
+  automatically switches to non-sticky mode.

pyproject.toml

@@ -2,7 +2,7 @@
 package = "tractor"
 filename = "NEWS.rst"
 directory = "nooz/"
-version = "0.1.0a5"
+version = "0.1.0a6"
 title_format = "tractor {version} ({project_date})"
 template = "nooz/_template.rst"
 all_bullets = true

requirements-test.txt

@@ -1,7 +1,7 @@
 pytest
 pytest-trio
 pytest-timeout
-pdbpp
+pdbp
 mypy
 trio_typing
 pexpect

setup.py

@@ -26,38 +26,41 @@ with open('docs/README.rst', encoding='utf-8') as f:
 setup(
     name="tractor",
     version='0.1.0a6dev0',  # alpha zone
-    description='structured concurrrent "actors"',
+    description='structured concurrrent `trio`-"actors"',
     long_description=readme,
     license='AGPLv3',
     author='Tyler Goodlet',
     maintainer='Tyler Goodlet',
-    maintainer_email='jgbt@protonmail.com',
+    maintainer_email='goodboy_foss@protonmail.com',
     url='https://github.com/goodboy/tractor',
     platforms=['linux', 'windows'],
     packages=[
         'tractor',
         'tractor.experimental',
         'tractor.trionics',
-        'tractor.testing',
     ],
     install_requires=[
 
         # trio related
-        'trio >= 0.20',
+        # proper range spec:
+        # https://packaging.python.org/en/latest/discussions/install-requires-vs-requirements/#id5
+        'trio >= 0.22',
         'async_generator',
         'trio_typing',
+        'exceptiongroup',
 
         # tooling
         'tricycle',
         'trio_typing',
-
-        # tooling
         'colorlog',
         'wrapt',
 
-        # serialization
+        # IPC serialization
         'msgspec',
 
+        # debug mode REPL
+        'pdbp',
+
         # pip ref docs on these specs:
         # https://pip.pypa.io/en/stable/reference/requirement-specifiers/#examples
         # and pep:
@@ -68,14 +71,9 @@ setup(
         # https://github.com/pdbpp/fancycompleter/issues/37
         'pyreadline3 ; platform_system == "Windows"',
 
-        # 3.10 has an outstanding unreleased issue and `pdbpp` itself
-        #   pins to patched forks of its own dependencies as well..and
-        #   we need a specific patch on master atm.
-        'pdbpp @ git+https://github.com/pdbpp/pdbpp@76c4be5#egg=pdbpp ; python_version > "3.9"',  # noqa: E501
-
     ],
     tests_require=['pytest'],
-    python_requires=">=3.9",
+    python_requires=">=3.10",
     keywords=[
         'trio',
         'async',

tests/conftest.py

@@ -7,16 +7,91 @@ import os
 import random
 import signal
 import platform
+import pathlib
 import time
+import inspect
+from functools import partial, wraps
 
 import pytest
+import trio
 import tractor
 
-# export for tests
-from tractor.testing import tractor_test  # noqa
-
-
 pytest_plugins = ['pytester']
+
+
+def tractor_test(fn):
+    """
+    Use:
+
+    @tractor_test
+    async def test_whatever():
+        await ...
+
+    If fixtures:
+
+        - ``arb_addr`` (a socket addr tuple where arbiter is listening)
+        - ``loglevel`` (logging level passed to tractor internals)
+        - ``start_method`` (subprocess spawning backend)
+
+    are defined in the `pytest` fixture space they will be automatically
+    injected to tests declaring these funcargs.
+    """
+    @wraps(fn)
+    def wrapper(
+        *args,
+        loglevel=None,
+        arb_addr=None,
+        start_method=None,
+        **kwargs
+    ):
+        # __tracebackhide__ = True
+
+        if 'arb_addr' in inspect.signature(fn).parameters:
+            # injects test suite fixture value to test as well
+            # as `run()`
+            kwargs['arb_addr'] = arb_addr
+
+        if 'loglevel' in inspect.signature(fn).parameters:
+            # allows test suites to define a 'loglevel' fixture
+            # that activates the internal logging
+            kwargs['loglevel'] = loglevel
+
+        if start_method is None:
+            if platform.system() == "Windows":
+                start_method = 'trio'
+
+        if 'start_method' in inspect.signature(fn).parameters:
+            # set of subprocess spawning backends
+            kwargs['start_method'] = start_method
+
+        if kwargs:
+
+            # use explicit root actor start
+
+            async def _main():
+                async with tractor.open_root_actor(
+                    # **kwargs,
+                    arbiter_addr=arb_addr,
+                    loglevel=loglevel,
+                    start_method=start_method,
+
+                    # TODO: only enable when pytest is passed --pdb
+                    # debug_mode=True,
+
+                ):
+                    await fn(*args, **kwargs)
+
+            main = _main
+
+        else:
+            # use implicit root actor start
+            main = partial(fn, *args, **kwargs)
+
+        return trio.run(main)
+
+    return wrapper
+
+
 _arb_addr = '127.0.0.1', random.randint(1000, 9999)
 
 
@@ -39,14 +114,21 @@ no_windows = pytest.mark.skipif(
 )
 
 
-def repodir():
-    """Return the abspath to the repo directory.
-    """
-    dirname = os.path.dirname
-    dirpath = os.path.abspath(
-        dirname(dirname(os.path.realpath(__file__)))
-        )
-    return dirpath
+def repodir() -> pathlib.Path:
+    '''
+    Return the abspath to the repo directory.
+
+    '''
+    # 2 parents up to step up through tests/<repo_dir>
+    return pathlib.Path(__file__).parent.parent.absolute()
+
+
+def examples_dir() -> pathlib.Path:
+    '''
+    Return the abspath to the examples directory as `pathlib.Path`.
+
+    '''
+    return repodir() / 'examples'
 
 
 def pytest_addoption(parser):
@@ -64,10 +146,6 @@ def pytest_addoption(parser):
 
 def pytest_configure(config):
     backend = config.option.spawn_backend
-
-    if backend == 'mp':
-        tractor._spawn.try_set_start_method('spawn')
-    elif backend == 'trio':
     tractor._spawn.try_set_start_method(backend)
 
 
@@ -81,7 +159,7 @@ def loglevel(request):
 
 
 @pytest.fixture(scope='session')
-def spawn_backend(request):
+def spawn_backend(request) -> str:
     return request.config.option.spawn_backend
 
 
@@ -102,24 +180,24 @@ def arb_addr():
 
 def pytest_generate_tests(metafunc):
     spawn_backend = metafunc.config.option.spawn_backend
+
     if not spawn_backend:
         # XXX some weird windows bug with `pytest`?
-        spawn_backend = 'mp'
-    assert spawn_backend in ('mp', 'trio')
+        spawn_backend = 'trio'
 
+    # TODO: maybe just use the literal `._spawn.SpawnMethodKey`?
+    assert spawn_backend in (
+        'mp_spawn',
+        'mp_forkserver',
+        'trio',
+    )
+
+    # NOTE: used to be used to dyanmically parametrize tests for when
+    # you just passed --spawn-backend=`mp` on the cli, but now we expect
+    # that cli input to be manually specified, BUT, maybe we'll do
+    # something like this again in the future?
     if 'start_method' in metafunc.fixturenames:
-        if spawn_backend == 'mp':
-            from multiprocessing import get_all_start_methods
-            methods = get_all_start_methods()
-            if 'fork' in methods:
-                # fork not available on windows, so check before
-                # removing XXX: the fork method is in general
-                # incompatible with trio's global scheduler state
-                methods.remove('fork')
-        elif spawn_backend == 'trio':
-            methods = ['trio']
-
-        metafunc.parametrize("start_method", methods, scope='module')
+        metafunc.parametrize("start_method", [spawn_backend], scope='module')
 
 
 def sig_prog(proc, sig):
@@ -135,16 +213,22 @@ def sig_prog(proc, sig):
 
 
 @pytest.fixture
-def daemon(loglevel, testdir, arb_addr):
-    """Run a daemon actor as a "remote arbiter".
-    """
+def daemon(
+    loglevel: str,
+    testdir,
+    arb_addr: tuple[str, int],
+):
+    '''
+    Run a daemon actor as a "remote arbiter".
+
+    '''
     if loglevel in ('trace', 'debug'):
         # too much logging will lock up the subproc (smh)
         loglevel = 'info'
 
     cmdargs = [
         sys.executable, '-c',
-        "import tractor; tractor.run_daemon([], arbiter_addr={}, loglevel={})"
+        "import tractor; tractor.run_daemon([], registry_addr={}, loglevel={})"
         .format(
             arb_addr,
             "'{}'".format(loglevel) if loglevel else None)

tests/test_advanced_faults.py

@@ -0,0 +1,193 @@
+'''
+Sketchy network blackoutz, ugly byzantine gens, puedes eschuchar la
+cancelacion?..
+
+'''
+from functools import partial
+
+import pytest
+from _pytest.pathlib import import_path
+import trio
+import tractor
+
+from conftest import (
+    examples_dir,
+)
+
+
+@pytest.mark.parametrize(
+    'debug_mode',
+    [False, True],
+    ids=['no_debug_mode', 'debug_mode'],
+)
+@pytest.mark.parametrize(
+    'ipc_break',
+    [
+        # no breaks
+        {
+            'break_parent_ipc_after': False,
+            'break_child_ipc_after': False,
+        },
+
+        # only parent breaks
+        {
+            'break_parent_ipc_after': 500,
+            'break_child_ipc_after': False,
+        },
+
+        # only child breaks
+        {
+            'break_parent_ipc_after': False,
+            'break_child_ipc_after': 500,
+        },
+
+        # both: break parent first
+        {
+            'break_parent_ipc_after': 500,
+            'break_child_ipc_after': 800,
+        },
+        # both: break child first
+        {
+            'break_parent_ipc_after': 800,
+            'break_child_ipc_after': 500,
+        },
+
+    ],
+    ids=[
+        'no_break',
+        'break_parent',
+        'break_child',
+        'break_both_parent_first',
+        'break_both_child_first',
+    ],
+)
+def test_ipc_channel_break_during_stream(
+    debug_mode: bool,
+    spawn_backend: str,
+    ipc_break: dict | None,
+):
+    '''
+    Ensure we can have an IPC channel break its connection during
+    streaming and it's still possible for the (simulated) user to kill
+    the actor tree using SIGINT.
+
+    We also verify the type of connection error expected in the parent
+    depending on which side if the IPC breaks first.
+
+    '''
+    if spawn_backend != 'trio':
+        if debug_mode:
+            pytest.skip('`debug_mode` only supported on `trio` spawner')
+
+        # non-`trio` spawners should never hit the hang condition that
+        # requires the user to do ctl-c to cancel the actor tree.
+        expect_final_exc = trio.ClosedResourceError
+
+    mod = import_path(
+        examples_dir() / 'advanced_faults' / 'ipc_failure_during_stream.py',
+        root=examples_dir(),
+    )
+
+    expect_final_exc = KeyboardInterrupt
+
+    # when ONLY the child breaks we expect the parent to get a closed
+    # resource error on the next `MsgStream.receive()` and then fail out
+    # and cancel the child from there.
+    if (
+
+        # only child breaks
+        (
+            ipc_break['break_child_ipc_after']
+            and ipc_break['break_parent_ipc_after'] is False
+        )
+
+        # both break but, parent breaks first
+        or (
+            ipc_break['break_child_ipc_after'] is not False
+            and (
+                ipc_break['break_parent_ipc_after']
+                > ipc_break['break_child_ipc_after']
+            )
+        )
+
+    ):
+        expect_final_exc = trio.ClosedResourceError
+
+    # when the parent IPC side dies (even if the child's does as well
+    # but the child fails BEFORE the parent) we expect the channel to be
+    # sent a stop msg from the child at some point which will signal the
+    # parent that the stream has been terminated.
+    # NOTE: when the parent breaks "after" the child you get this same
+    # case as well, the child breaks the IPC channel with a stop msg
+    # before any closure takes place.
+    elif (
+        # only parent breaks
+        (
+            ipc_break['break_parent_ipc_after']
+            and ipc_break['break_child_ipc_after'] is False
+        )
+
+        # both break but, child breaks first
+        or (
+            ipc_break['break_parent_ipc_after'] is not False
+            and (
+                ipc_break['break_child_ipc_after']
+                > ipc_break['break_parent_ipc_after']
+            )
+        )
+    ):
+        expect_final_exc = trio.EndOfChannel
+
+    with pytest.raises(expect_final_exc):
+        trio.run(
+            partial(
+                mod.main,
+                debug_mode=debug_mode,
+                start_method=spawn_backend,
+                **ipc_break,
+            )
+        )
+
+
+@tractor.context
+async def break_ipc_after_started(
+    ctx: tractor.Context,
+) -> None:
+    await ctx.started()
+    async with ctx.open_stream() as stream:
+        await stream.aclose()
+        await trio.sleep(0.2)
+        await ctx.chan.send(None)
+        print('child broke IPC and terminating')
+
+
+def test_stream_closed_right_after_ipc_break_and_zombie_lord_engages():
+    '''
+    Verify that is a subactor's IPC goes down just after bringing up a stream
+    the parent can trigger a SIGINT and the child will be reaped out-of-IPC by
+    the localhost process supervision machinery: aka "zombie lord".
+
+    '''
+    async def main():
+        async with tractor.open_nursery() as n:
+            portal = await n.start_actor(
+                'ipc_breaker',
+                enable_modules=[__name__],
+            )
+
+            with trio.move_on_after(1):
+                async with (
+                    portal.open_context(
+                        break_ipc_after_started
+                    ) as (ctx, sent),
+                ):
+                    async with ctx.open_stream():
+                        await trio.sleep(0.5)
+
+                    print('parent waiting on context')
+
+            print('parent exited context')
+            raise KeyboardInterrupt
+
+    with pytest.raises(KeyboardInterrupt):
+        trio.run(main)

tests/test_advanced_streaming.py

@@ -14,7 +14,7 @@ def is_win():
     return platform.system() == 'Windows'
 
 
-_registry: dict[str, set[tractor.ReceiveMsgStream]] = {
+_registry: dict[str, set[tractor.MsgStream]] = {
     'even': set(),
     'odd': set(),
 }

tests/test_cancellation.py

@@ -8,6 +8,10 @@ import platform
 import time
 from itertools import repeat
 
+from exceptiongroup import (
+    BaseExceptionGroup,
+    ExceptionGroup,
+)
 import pytest
 import trio
 import tractor
@@ -56,29 +60,49 @@ def test_remote_error(arb_addr, args_err):
             arbiter_addr=arb_addr,
         ) as nursery:
 
+            # on a remote type error caused by bad input args
+            # this should raise directly which means we **don't** get
+            # an exception group outside the nursery since the error
+            # here and the far end task error are one in the same?
             portal = await nursery.run_in_actor(
                 assert_err, name='errorer', **args
             )
 
             # get result(s) from main task
             try:
+                # this means the root actor will also raise a local
+                # parent task error and thus an eg will propagate out
+                # of this actor nursery.
                 await portal.result()
             except tractor.RemoteActorError as err:
                 assert err.type == errtype
                 print("Look Maa that actor failed hard, hehh")
                 raise
 
+    # ensure boxed errors
+    if args:
         with pytest.raises(tractor.RemoteActorError) as excinfo:
             trio.run(main)
 
-    # ensure boxed error is correct
         assert excinfo.value.type == errtype
 
+    else:
+        # the root task will also error on the `.result()` call
+        # so we expect an error from there AND the child.
+        with pytest.raises(BaseExceptionGroup) as excinfo:
+            trio.run(main)
+
+        # ensure boxed errors
+        for exc in excinfo.value.exceptions:
+            assert exc.type == errtype
+
 
 def test_multierror(arb_addr):
-    """Verify we raise a ``trio.MultiError`` out of a nursery where
+    '''
+    Verify we raise a ``BaseExceptionGroup`` out of a nursery where
     more then one actor errors.
-    """
+
+    '''
     async def main():
         async with tractor.open_nursery(
             arbiter_addr=arb_addr,
@@ -95,10 +119,10 @@ def test_multierror(arb_addr):
                 print("Look Maa that first actor failed hard, hehh")
                 raise
 
-        # here we should get a `trio.MultiError` containing exceptions
+        # here we should get a ``BaseExceptionGroup`` containing exceptions
         # from both subactors
 
-    with pytest.raises(trio.MultiError):
+    with pytest.raises(BaseExceptionGroup):
         trio.run(main)
 
 
@@ -107,7 +131,7 @@ def test_multierror(arb_addr):
     'num_subactors', range(25, 26),
 )
 def test_multierror_fast_nursery(arb_addr, start_method, num_subactors, delay):
-    """Verify we raise a ``trio.MultiError`` out of a nursery where
+    """Verify we raise a ``BaseExceptionGroup`` out of a nursery where
     more then one actor errors and also with a delay before failure
     to test failure during an ongoing spawning.
     """
@@ -123,10 +147,11 @@ def test_multierror_fast_nursery(arb_addr, start_method, num_subactors, delay):
                     delay=delay
                 )
 
-    with pytest.raises(trio.MultiError) as exc_info:
+    # with pytest.raises(trio.MultiError) as exc_info:
+    with pytest.raises(BaseExceptionGroup) as exc_info:
         trio.run(main)
 
-    assert exc_info.type == tractor.MultiError
+    assert exc_info.type == ExceptionGroup
     err = exc_info.value
     exceptions = err.exceptions
 
@@ -214,8 +239,8 @@ async def test_cancel_infinite_streamer(start_method):
     [
         # daemon actors sit idle while single task actors error out
         (1, tractor.RemoteActorError, AssertionError, (assert_err, {}), None),
-        (2, tractor.MultiError, AssertionError, (assert_err, {}), None),
-        (3, tractor.MultiError, AssertionError, (assert_err, {}), None),
+        (2, BaseExceptionGroup, AssertionError, (assert_err, {}), None),
+        (3, BaseExceptionGroup, AssertionError, (assert_err, {}), None),
 
         # 1 daemon actor errors out while single task actors sleep forever
         (3, tractor.RemoteActorError, AssertionError, (sleep_forever, {}),
@@ -226,7 +251,7 @@ async def test_cancel_infinite_streamer(start_method):
          (do_nuthin, {}), (assert_err, {'delay': 1}, True)),
         # daemon complete quickly delay while single task
         # actors error after brief delay
-        (3, tractor.MultiError, AssertionError,
+        (3, BaseExceptionGroup, AssertionError,
          (assert_err, {'delay': 1}), (do_nuthin, {}, False)),
     ],
     ids=[
@@ -293,7 +318,7 @@ async def test_some_cancels_all(num_actors_and_errs, start_method, loglevel):
         # should error here with a ``RemoteActorError`` or ``MultiError``
 
     except first_err as err:
-        if isinstance(err, tractor.MultiError):
+        if isinstance(err, BaseExceptionGroup):
             assert len(err.exceptions) == num_actors
             for exc in err.exceptions:
                 if isinstance(exc, tractor.RemoteActorError):
@@ -337,7 +362,7 @@ async def spawn_and_error(breadth, depth) -> None:
 @tractor_test
 async def test_nested_multierrors(loglevel, start_method):
     '''
-    Test that failed actor sets are wrapped in `trio.MultiError`s. This
+    Test that failed actor sets are wrapped in `BaseExceptionGroup`s. This
     test goes only 2 nurseries deep but we should eventually have tests
     for arbitrary n-depth actor trees.
 
@@ -365,7 +390,7 @@ async def test_nested_multierrors(loglevel, start_method):
                         breadth=subactor_breadth,
                         depth=depth,
                     )
-        except trio.MultiError as err:
+        except BaseExceptionGroup as err:
             assert len(err.exceptions) == subactor_breadth
             for subexc in err.exceptions:
 
@@ -383,10 +408,10 @@ async def test_nested_multierrors(loglevel, start_method):
                         assert subexc.type in (
                             tractor.RemoteActorError,
                             trio.Cancelled,
-                            trio.MultiError
+                            BaseExceptionGroup,
                         )
 
-                    elif isinstance(subexc, trio.MultiError):
+                    elif isinstance(subexc, BaseExceptionGroup):
                         for subsub in subexc.exceptions:
 
                             if subsub in (tractor.RemoteActorError,):
@@ -394,7 +419,7 @@ async def test_nested_multierrors(loglevel, start_method):
 
                             assert type(subsub) in (
                                 trio.Cancelled,
-                                trio.MultiError,
+                                BaseExceptionGroup,
                             )
                 else:
                     assert isinstance(subexc, tractor.RemoteActorError)
@@ -406,13 +431,13 @@ async def test_nested_multierrors(loglevel, start_method):
                     if is_win():
                         if isinstance(subexc, tractor.RemoteActorError):
                             assert subexc.type in (
-                                trio.MultiError,
+                                BaseExceptionGroup,
                                 tractor.RemoteActorError
                             )
                         else:
-                            assert isinstance(subexc, trio.MultiError)
+                            assert isinstance(subexc, BaseExceptionGroup)
                     else:
-                        assert subexc.type is trio.MultiError
+                        assert subexc.type is ExceptionGroup
                 else:
                     assert subexc.type in (
                         tractor.RemoteActorError,
@@ -435,7 +460,7 @@ def test_cancel_via_SIGINT(
         with trio.fail_after(2):
             async with tractor.open_nursery() as tn:
                 await tn.start_actor('sucka')
-                if spawn_backend == 'mp':
+                if 'mp' in spawn_backend:
                     time.sleep(0.1)
                 os.kill(pid, signal.SIGINT)
                 await trio.sleep_forever()
@@ -474,7 +499,7 @@ def test_cancel_via_SIGINT_other_task(
         with trio.fail_after(timeout):
             async with trio.open_nursery() as n:
                 await n.start(spawn_and_sleep_forever)
-                if spawn_backend == 'mp':
+                if 'mp' in spawn_backend:
                     time.sleep(0.1)
                 os.kill(pid, signal.SIGINT)
 

tests/test_clustering.py

@@ -1,5 +1,6 @@
 import itertools
 
+import pytest
 import trio
 import tractor
 from tractor import open_actor_cluster
@@ -11,26 +12,72 @@ from conftest import tractor_test
 MESSAGE = 'tractoring at full speed'
 
 
+def test_empty_mngrs_input_raises() -> None:
+
+    async def main():
+        with trio.fail_after(1):
+            async with (
+                open_actor_cluster(
+                    modules=[__name__],
+
+                    # NOTE: ensure we can passthrough runtime opts
+                    loglevel='info',
+                    # debug_mode=True,
+
+                ) as portals,
+
+                gather_contexts(
+                    # NOTE: it's the use of inline-generator syntax
+                    # here that causes the empty input.
+                    mngrs=(
+                        p.open_context(worker) for p in portals.values()
+                    ),
+                ),
+            ):
+                assert 0
+
+    with pytest.raises(ValueError):
+        trio.run(main)
+
+
 @tractor.context
-async def worker(ctx: tractor.Context) -> None:
+async def worker(
+    ctx: tractor.Context,
+
+) -> None:
+
     await ctx.started()
-    async with ctx.open_stream(backpressure=True) as stream:
+
+    async with ctx.open_stream(
+        backpressure=True,
+    ) as stream:
+
+        # TODO: this with the below assert causes a hang bug?
+        # with trio.move_on_after(1):
+
         async for msg in stream:
             # do something with msg
             print(msg)
             assert msg == MESSAGE
 
+        # TODO: does this ever cause a hang
+        # assert 0
+
 
 @tractor_test
 async def test_streaming_to_actor_cluster() -> None:
+
     async with (
         open_actor_cluster(modules=[__name__]) as portals,
+
         gather_contexts(
             mngrs=[p.open_context(worker) for p in portals.values()],
         ) as contexts,
+
         gather_contexts(
             mngrs=[ctx[0].open_stream() for ctx in contexts],
         ) as streams,
+
     ):
         with trio.move_on_after(1):
             for stream in itertools.cycle(streams):

tests/test_debugger.py

@@ -10,9 +10,11 @@ TODO:
     - wonder if any of it'll work on OS X?
 
 """
+import itertools
 from os import path
 from typing import Optional
 import platform
+import pathlib
 import sys
 import time
 
@@ -23,7 +25,10 @@ from pexpect.exceptions import (
     EOF,
 )
 
-from conftest import repodir, _ci_env
+from conftest import (
+    examples_dir,
+    _ci_env,
+)
 
 # TODO: The next great debugger audit could be done by you!
 # - recurrent entry to breakpoint() from single actor *after* and an
@@ -42,19 +47,13 @@ if platform.system() == 'Windows':
     )
 
 
-def examples_dir():
-    """Return the abspath to the examples directory.
-    """
-    return path.join(repodir(), 'examples', 'debugging/')
-
-
 def mk_cmd(ex_name: str) -> str:
-    """Generate a command suitable to pass to ``pexpect.spawn()``.
-    """
-    return ' '.join(
-        ['python',
-         path.join(examples_dir(), f'{ex_name}.py')]
-    )
+    '''
+    Generate a command suitable to pass to ``pexpect.spawn()``.
+
+    '''
+    script_path: pathlib.Path = examples_dir() / 'debugging' / f'{ex_name}.py'
+    return ' '.join(['python', str(script_path)])
 
 
 # TODO: was trying to this xfail style but some weird bug i see in CI
@@ -96,7 +95,7 @@ def spawn(
     return _spawn
 
 
-PROMPT = r"\(Pdb\+\+\)"
+PROMPT = r"\(Pdb\+\)"
 
 
 def expect(
@@ -152,27 +151,14 @@ def ctlc(
 
     use_ctlc = request.param
 
-    if (
-        sys.version_info <= (3, 10)
-        and use_ctlc
-    ):
-        # on 3.9 it seems the REPL UX
-        # is highly unreliable and frankly annoying
-        # to test for. It does work from manual testing
-        # but i just don't think it's wroth it to try
-        # and get this working especially since we want to
-        # be 3.10+ mega-asap.
-        pytest.skip('Py3.9 and `pdbpp` son no bueno..')
-
-    if ci_env:
     node = request.node
     markers = node.own_markers
     for mark in markers:
         if mark.name == 'has_nested_actors':
             pytest.skip(
-                    f'Test for {node} uses nested actors and fails in CI\n'
-                    f'The test seems to run fine locally but until we solve'
-                    'this issue this CI test will be xfail:\n'
+                f'Test {node} has nested actors and fails with Ctrl-C.\n'
+                f'The test can sometimes run fine locally but until'
+                ' we solve' 'this issue this CI test will be xfail:\n'
                 'https://github.com/goodboy/tractor/issues/320'
             )
 
@@ -195,13 +181,15 @@ def ctlc(
     ids=lambda item: f'{item[0]} -> {item[1]}',
 )
 def test_root_actor_error(spawn, user_in_out):
-    """Demonstrate crash handler entering pdbpp from basic error in root actor.
-    """
+    '''
+    Demonstrate crash handler entering pdb from basic error in root actor.
+
+    '''
     user_input, expect_err_str = user_in_out
 
     child = spawn('root_actor_error')
 
-    # scan for the pdbpp prompt
+    # scan for the prompt
     expect(child, PROMPT)
 
     before = str(child.before.decode())
@@ -232,8 +220,8 @@ def test_root_actor_bp(spawn, user_in_out):
     user_input, expect_err_str = user_in_out
     child = spawn('root_actor_breakpoint')
 
-    # scan for the pdbpp prompt
-    child.expect(r"\(Pdb\+\+\)")
+    # scan for the prompt
+    child.expect(PROMPT)
 
     assert 'Error' not in str(child.before)
 
@@ -274,7 +262,7 @@ def do_ctlc(
         if expect_prompt:
             before = str(child.before.decode())
             time.sleep(delay)
-            child.expect(r"\(Pdb\+\+\)")
+            child.expect(PROMPT)
             time.sleep(delay)
 
             if patt:
@@ -293,7 +281,7 @@ def test_root_actor_bp_forever(
     # entries
     for _ in range(10):
 
-        child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
 
         if ctlc:
             do_ctlc(child)
@@ -303,7 +291,7 @@ def test_root_actor_bp_forever(
     # do one continue which should trigger a
     # new task to lock the tty
     child.sendline('continue')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     # seems that if we hit ctrl-c too fast the
     # sigint guard machinery might not kick in..
@@ -314,10 +302,10 @@ def test_root_actor_bp_forever(
 
     # XXX: this previously caused a bug!
     child.sendline('n')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     child.sendline('n')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     # quit out of the loop
     child.sendline('q')
@@ -340,8 +328,8 @@ def test_subactor_error(
     '''
     child = spawn('subactor_error')
 
-    # scan for the pdbpp prompt
-    child.expect(r"\(Pdb\+\+\)")
+    # scan for the prompt
+    child.expect(PROMPT)
 
     before = str(child.before.decode())
     assert "Attaching to pdb in crashed actor: ('name_error'" in before
@@ -361,7 +349,7 @@ def test_subactor_error(
         # creating actor
         child.sendline('continue')
 
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
     before = str(child.before.decode())
 
     # root actor gets debugger engaged
@@ -388,8 +376,8 @@ def test_subactor_breakpoint(
 
     child = spawn('subactor_breakpoint')
 
-    # scan for the pdbpp prompt
-    child.expect(r"\(Pdb\+\+\)")
+    # scan for the prompt
+    child.expect(PROMPT)
 
     before = str(child.before.decode())
     assert "Attaching pdb to actor: ('breakpoint_forever'" in before
@@ -398,7 +386,7 @@ def test_subactor_breakpoint(
     # entries
     for _ in range(10):
         child.sendline('next')
-        child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
 
         if ctlc:
             do_ctlc(child)
@@ -406,7 +394,7 @@ def test_subactor_breakpoint(
     # now run some "continues" to show re-entries
     for _ in range(5):
         child.sendline('continue')
-        child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
         before = str(child.before.decode())
         assert "Attaching pdb to actor: ('breakpoint_forever'" in before
 
@@ -417,7 +405,7 @@ def test_subactor_breakpoint(
     child.sendline('q')
 
     # child process should exit but parent will capture pdb.BdbQuit
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     before = str(child.before.decode())
     assert "RemoteActorError: ('breakpoint_forever'" in before
@@ -449,8 +437,8 @@ def test_multi_subactors(
     '''
     child = spawn(r'multi_subactors')
 
-    # scan for the pdbpp prompt
-    child.expect(r"\(Pdb\+\+\)")
+    # scan for the prompt
+    child.expect(PROMPT)
 
     before = str(child.before.decode())
     assert "Attaching pdb to actor: ('breakpoint_forever'" in before
@@ -462,7 +450,7 @@ def test_multi_subactors(
     # entries
     for _ in range(10):
         child.sendline('next')
-        child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
 
         if ctlc:
             do_ctlc(child)
@@ -471,7 +459,7 @@ def test_multi_subactors(
     child.sendline('c')
 
     # first name_error failure
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
     before = str(child.before.decode())
     assert "Attaching to pdb in crashed actor: ('name_error'" in before
     assert "NameError" in before
@@ -483,19 +471,21 @@ def test_multi_subactors(
     child.sendline('c')
 
     # 2nd name_error failure
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
-    assert_before(child, [
-        "Attaching to pdb in crashed actor: ('name_error_1'",
-        "NameError",
-    ])
+    # TODO: will we ever get the race where this crash will show up?
+    # blocklist strat now prevents this crash
+    # assert_before(child, [
+    #     "Attaching to pdb in crashed actor: ('name_error_1'",
+    #     "NameError",
+    # ])
 
     if ctlc:
         do_ctlc(child)
 
     # breakpoint loop should re-engage
     child.sendline('c')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
     before = str(child.before.decode())
     assert "Attaching pdb to actor: ('breakpoint_forever'" in before
 
@@ -511,7 +501,7 @@ def test_multi_subactors(
     ):
         child.sendline('c')
         time.sleep(0.1)
-        child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
         before = str(child.before.decode())
 
         if ctlc:
@@ -530,11 +520,11 @@ def test_multi_subactors(
     # now run some "continues" to show re-entries
     for _ in range(5):
         child.sendline('c')
-        child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
 
     # quit the loop and expect parent to attach
     child.sendline('q')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
     before = str(child.before.decode())
 
     assert_before(child, [
@@ -578,16 +568,16 @@ def test_multi_daemon_subactors(
     '''
     child = spawn('multi_daemon_subactors')
 
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
-    # there is a race for which subactor will acquire
-    # the root's tty lock first
-
-    before = str(child.before.decode())
+    # there can be a race for which subactor will acquire
+    # the root's tty lock first so anticipate either crash
+    # message on the first entry.
 
     bp_forever_msg = "Attaching pdb to actor: ('bp_forever'"
-    name_error_msg = "NameError"
+    name_error_msg = "NameError: name 'doggypants' is not defined"
 
+    before = str(child.before.decode())
     if bp_forever_msg in before:
         next_msg = name_error_msg
 
@@ -608,10 +598,8 @@ def test_multi_daemon_subactors(
     # second entry by `bp_forever`.
 
     child.sendline('c')
-    child.expect(r"\(Pdb\+\+\)")
-    before = str(child.before.decode())
-
-    assert next_msg in before
+    child.expect(PROMPT)
+    assert_before(child, [next_msg])
 
     # XXX: hooray the root clobbering the child here was fixed!
     # IMO, this demonstrates the true power of SC system design.
@@ -630,31 +618,50 @@ def test_multi_daemon_subactors(
     if ctlc:
         do_ctlc(child)
 
-    # wait for final error in root
-    while True:
-
+    # expect another breakpoint actor entry
     child.sendline('c')
-        child.expect(r"\(Pdb\+\+\)")
-        before = str(child.before.decode())
+    child.expect(PROMPT)
+
     try:
-
-            # root error should be packed as remote error
-            assert "_exceptions.RemoteActorError: ('name_error'" in before
-            break
-
+        assert_before(child, [bp_forever_msg])
     except AssertionError:
-            assert bp_forever_msg in before
+        assert_before(child, [name_error_msg])
 
+    else:
         if ctlc:
             do_ctlc(child)
 
+        # should crash with the 2nd name error (simulates
+        # a retry) and then the root eventually (boxed) errors
+        # after 1 or more further bp actor entries.
+
+        child.sendline('c')
+        child.expect(PROMPT)
+        assert_before(child, [name_error_msg])
+
+    # wait for final error in root
+    # where it crashs with boxed error
+    while True:
         try:
             child.sendline('c')
-        child.expect(pexpect.EOF)
+            child.expect(PROMPT)
+            assert_before(
+                child,
+                [bp_forever_msg]
+            )
+        except AssertionError:
+            break
 
-    except TIMEOUT:
-        # Failed to exit using continue..?
-        child.sendline('q')
+    assert_before(
+        child,
+        [
+            # boxed error raised in root task
+            "Attaching to pdb in crashed actor: ('root'",
+            "_exceptions.RemoteActorError: ('name_error'",
+        ]
+    )
+
+    child.sendline('c')
     child.expect(pexpect.EOF)
 
 
@@ -670,8 +677,8 @@ def test_multi_subactors_root_errors(
     '''
     child = spawn('multi_subactor_root_errors')
 
-    # scan for the pdbpp prompt
-    child.expect(r"\(Pdb\+\+\)")
+    # scan for the prompt
+    child.expect(PROMPT)
 
     # at most one subactor should attach before the root is cancelled
     before = str(child.before.decode())
@@ -683,7 +690,15 @@ def test_multi_subactors_root_errors(
     # continue again to catch 2nd name error from
     # actor 'name_error_1' (which is 2nd depth).
     child.sendline('c')
-    child.expect(r"\(Pdb\+\+\)")
+
+    # due to block list strat from #337, this will no longer
+    # propagate before the root errors and cancels the spawner sub-tree.
+    child.expect(PROMPT)
+
+    # only if the blocking condition doesn't kick in fast enough
+    before = str(child.before.decode())
+    if "Debug lock blocked for ['name_error_1'" not in before:
+
         assert_before(child, [
             "Attaching to pdb in crashed actor: ('name_error_1'",
             "NameError",
@@ -693,10 +708,15 @@ def test_multi_subactors_root_errors(
             do_ctlc(child)
 
         child.sendline('c')
-    child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
+
+    # check if the spawner crashed or was blocked from debug
+    # and if this intermediary attached check the boxed error
+    before = str(child.before.decode())
+    if "Attaching to pdb in crashed actor: ('spawn_error'" in before:
+
         assert_before(child, [
-        "Attaching to pdb in crashed actor: ('spawn_error'",
-        # boxed error from previous step
+            # boxed error from spawner's child
             "RemoteActorError: ('name_error_1'",
             "NameError",
         ])
@@ -705,27 +725,29 @@ def test_multi_subactors_root_errors(
             do_ctlc(child)
 
         child.sendline('c')
-    child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
+
+    # expect a root actor crash
     assert_before(child, [
-        "Attaching to pdb in crashed actor: ('root'",
-        # boxed error from previous step
         "RemoteActorError: ('name_error'",
         "NameError",
+
+        # error from root actor and root task that created top level nursery
+        "Attaching to pdb in crashed actor: ('root'",
+        "AssertionError",
     ])
 
-    # warnings assert we probably don't need
-    # assert "Cancelling nursery in ('spawn_error'," in before
-
-    if ctlc:
-        do_ctlc(child)
-
-    # continue again
     child.sendline('c')
     child.expect(pexpect.EOF)
 
-    before = str(child.before.decode())
-    # error from root actor and root task that created top level nursery
-    assert "AssertionError" in before
+    assert_before(child, [
+        # "Attaching to pdb in crashed actor: ('root'",
+        # boxed error from previous step
+        "RemoteActorError: ('name_error'",
+        "NameError",
+        "AssertionError",
+        'assert 0',
+    ])
 
 
 @has_nested_actors
@@ -750,24 +772,31 @@ def test_multi_nested_subactors_error_through_nurseries(
 
     timed_out_early: bool = False
 
-    for i in range(12):
+    for send_char in itertools.cycle(['c', 'q']):
         try:
-            child.expect(r"\(Pdb\+\+\)")
-            child.sendline('c')
-            time.sleep(0.1)
+            child.expect(PROMPT)
+            child.sendline(send_char)
+            time.sleep(0.01)
 
         except EOF:
-
-            # race conditions on how fast the continue is sent?
-            print(f"Failed early on {i}?")
-            timed_out_early = True
             break
-    else:
-        child.expect(pexpect.EOF)
 
-    if not timed_out_early:
-        before = str(child.before.decode())
-        assert "NameError" in before
+    assert_before(child, [
+
+        # boxed source errors
+        "NameError: name 'doggypants' is not defined",
+        "tractor._exceptions.RemoteActorError: ('name_error'",
+        "bdb.BdbQuit",
+
+        # first level subtrees
+        "tractor._exceptions.RemoteActorError: ('spawner0'",
+        # "tractor._exceptions.RemoteActorError: ('spawner1'",
+
+        # propagation of errors up through nested subtrees
+        "tractor._exceptions.RemoteActorError: ('spawn_until_0'",
+        "tractor._exceptions.RemoteActorError: ('spawn_until_1'",
+        "tractor._exceptions.RemoteActorError: ('spawn_until_2'",
+    ])
 
 
 @pytest.mark.timeout(15)
@@ -787,7 +816,7 @@ def test_root_nursery_cancels_before_child_releases_tty_lock(
 
     child = spawn('root_cancelled_but_child_is_in_tty_lock')
 
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     before = str(child.before.decode())
     assert "NameError: name 'doggypants' is not defined" in before
@@ -802,7 +831,7 @@ def test_root_nursery_cancels_before_child_releases_tty_lock(
     for i in range(4):
         time.sleep(0.5)
         try:
-            child.expect(r"\(Pdb\+\+\)")
+            child.expect(PROMPT)
 
         except (
             EOF,
@@ -859,7 +888,7 @@ def test_root_cancels_child_context_during_startup(
     '''
     child = spawn('fast_error_in_root_after_spawn')
 
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     before = str(child.before.decode())
     assert "AssertionError" in before
@@ -876,7 +905,7 @@ def test_different_debug_mode_per_actor(
     ctlc: bool,
 ):
     child = spawn('per_actor_debug')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     # only one actor should enter the debugger
     before = str(child.before.decode())

tests/test_docs_examples.py

@@ -12,17 +12,17 @@ import shutil
 
 import pytest
 
-from conftest import repodir
-
-
-def examples_dir():
-    """Return the abspath to the examples directory.
-    """
-    return os.path.join(repodir(), 'examples')
+from conftest import (
+    examples_dir,
+)
 
 
 @pytest.fixture
-def run_example_in_subproc(loglevel, testdir, arb_addr):
+def run_example_in_subproc(
+    loglevel: str,
+    testdir,
+    arb_addr: tuple[str, int],
+):
 
     @contextmanager
     def run(script_code):
@@ -32,8 +32,8 @@ def run_example_in_subproc(loglevel, testdir, arb_addr):
             # on windows we need to create a special __main__.py which will
             # be executed with ``python -m <modulename>`` on windows..
             shutil.copyfile(
-                os.path.join(examples_dir(), '__main__.py'),
-                os.path.join(str(testdir), '__main__.py')
+                examples_dir() / '__main__.py',
+                str(testdir / '__main__.py'),
             )
 
             # drop the ``if __name__ == '__main__'`` guard onwards from
@@ -88,6 +88,7 @@ def run_example_in_subproc(loglevel, testdir, arb_addr):
         and f[0] != '_'
         and 'debugging' not in p[0]
         and 'integration' not in p[0]
+        and 'advanced_faults' not in p[0]
     ],
 
     ids=lambda t: t[1],

tests/test_infected_asyncio.py

@@ -8,6 +8,7 @@ import builtins
 import itertools
 import importlib
 
+from exceptiongroup import BaseExceptionGroup
 import pytest
 import trio
 import tractor
@@ -170,11 +171,11 @@ async def trio_ctx(
     # message.
     with trio.fail_after(2):
         async with (
+            trio.open_nursery() as n,
+
             tractor.to_asyncio.open_channel_from(
                 sleep_and_err,
             ) as (first, chan),
-
-            trio.open_nursery() as n,
         ):
 
             assert first == 'start'
@@ -203,6 +204,7 @@ def test_context_spawns_aio_task_that_errors(
     '''
     async def main():
 
+        with trio.fail_after(2):
             async with tractor.open_nursery() as n:
                 p = await n.start_actor(
                     'aio_daemon',
@@ -408,11 +410,12 @@ def test_trio_error_cancels_intertask_chan(arb_addr):
             # should trigger remote actor error
             await portal.result()
 
-    with pytest.raises(RemoteActorError) as excinfo:
+    with pytest.raises(BaseExceptionGroup) as excinfo:
         trio.run(main)
 
-    # ensure boxed error is correct
-    assert excinfo.value.type == Exception
+    # ensure boxed errors
+    for exc in excinfo.value.exceptions:
+        assert exc.type == Exception
 
 
 def test_trio_closes_early_and_channel_exits(arb_addr):
@@ -441,11 +444,12 @@ def test_aio_errors_and_channel_propagates_and_closes(arb_addr):
             # should trigger remote actor error
             await portal.result()
 
-    with pytest.raises(RemoteActorError) as excinfo:
+    with pytest.raises(BaseExceptionGroup) as excinfo:
         trio.run(main)
 
-    # ensure boxed error is correct
-    assert excinfo.value.type == Exception
+    # ensure boxed errors
+    for exc in excinfo.value.exceptions:
+        assert exc.type == Exception
 
 
 @tractor.context

tests/test_legacy_one_way_streaming.py

@@ -7,9 +7,10 @@ import platform
 
 import trio
 import tractor
-from tractor.testing import tractor_test
 import pytest
 
+from conftest import tractor_test
+
 
 def test_must_define_ctx():
 
@@ -250,7 +251,7 @@ def test_a_quadruple_example(time_quad_ex, ci_env, spawn_backend):
 
     results, diff = time_quad_ex
     assert results
-    this_fast = 6 if platform.system() in ('Windows', 'Darwin') else 2.666
+    this_fast = 6 if platform.system() in ('Windows', 'Darwin') else 3
     assert diff < this_fast
 
 

tests/test_local.py

@@ -11,7 +11,7 @@ from conftest import tractor_test
 
 
 @pytest.mark.trio
-async def test_no_arbitter():
+async def test_no_runtime():
     """An arbitter must be established before any nurseries
     can be created.
 
@@ -19,7 +19,7 @@ async def test_no_arbitter():
     some point?)
     """
     with pytest.raises(RuntimeError) :
-        with tractor.open_nursery():
+        async with tractor.find_actor('doggy'):
             pass
 
 

tests/test_pubsub.py

@@ -4,9 +4,10 @@ from itertools import cycle
 import pytest
 import trio
 import tractor
-from tractor.testing import tractor_test
 from tractor.experimental import msgpub
 
+from conftest import tractor_test
+
 
 def test_type_checks():
 

tests/test_runtime.py

@@ -62,7 +62,10 @@ async def test_lifetime_stack_wipes_tmpfile(
                         )
                     ).result()
 
-    except tractor.RemoteActorError:
+    except (
+        tractor.RemoteActorError,
+        tractor.BaseExceptionGroup,
+    ):
         pass
 
     # tmp file should have been wiped by

tests/test_spawning.py

@@ -142,7 +142,7 @@ def test_loglevel_propagated_to_subactor(
     capfd,
     arb_addr,
 ):
-    if start_method == 'forkserver':
+    if start_method == 'mp_forkserver':
         pytest.skip(
             "a bug with `capfd` seems to make forkserver capture not work?")
 

tests/test_task_broadcasting.py

@@ -12,7 +12,10 @@ import pytest
 import trio
 from trio.lowlevel import current_task
 import tractor
-from tractor.trionics import broadcast_receiver, Lagged
+from tractor.trionics import (
+    broadcast_receiver,
+    Lagged,
+)
 
 
 @tractor.context
@@ -37,7 +40,7 @@ async def echo_sequences(
 
 async def ensure_sequence(
 
-    stream: tractor.ReceiveMsgStream,
+    stream: tractor.MsgStream,
     sequence: list,
     delay: Optional[float] = None,
 
@@ -211,7 +214,8 @@ def test_faster_task_to_recv_is_cancelled_by_slower(
     arb_addr,
     start_method,
 ):
-    '''Ensure that if a faster task consuming from a stream is cancelled
+    '''
+    Ensure that if a faster task consuming from a stream is cancelled
     the slower task can continue to receive all expected values.
 
     '''
@@ -460,3 +464,51 @@ def test_first_recver_is_cancelled():
                     assert value == 1
 
     trio.run(main)
+
+
+def test_no_raise_on_lag():
+    '''
+    Run a simple 2-task broadcast where one task is slow but configured
+    so that it does not raise `Lagged` on overruns using
+    `raise_on_lasg=False` and verify that the task does not raise.
+
+    '''
+    size = 100
+    tx, rx = trio.open_memory_channel(size)
+    brx = broadcast_receiver(rx, size)
+
+    async def slow():
+        async with brx.subscribe(
+            raise_on_lag=False,
+        ) as br:
+            async for msg in br:
+                print(f'slow task got: {msg}')
+                await trio.sleep(0.1)
+
+    async def fast():
+        async with brx.subscribe() as br:
+            async for msg in br:
+                print(f'fast task got: {msg}')
+
+    async def main():
+        async with (
+            tractor.open_root_actor(
+                # NOTE: so we see the warning msg emitted by the bcaster
+                # internals when the no raise flag is set.
+                loglevel='warning',
+            ),
+            trio.open_nursery() as n,
+        ):
+            n.start_soon(slow)
+            n.start_soon(fast)
+
+            for i in range(1000):
+                await tx.send(i)
+
+            # simulate user nailing ctl-c after realizing
+            # there's a lag in the slow task.
+            await trio.sleep(1)
+            raise KeyboardInterrupt
+
+    with pytest.raises(KeyboardInterrupt):
+        trio.run(main)

tractor/__init__.py

@@ -18,13 +18,12 @@
 tractor: structured concurrent "actors".
 
 """
-from trio import MultiError
+from exceptiongroup import BaseExceptionGroup
 
 from ._clustering import open_actor_cluster
 from ._ipc import Channel
 from ._streaming import (
     Context,
-    ReceiveMsgStream,
     MsgStream,
     stream,
     context,
@@ -45,7 +44,10 @@ from ._exceptions import (
     ModuleNotExposed,
     ContextCancelled,
 )
-from ._debug import breakpoint, post_mortem
+from ._debug import (
+    breakpoint,
+    post_mortem,
+)
 from . import msg
 from ._root import (
     run_daemon,
@@ -62,9 +64,8 @@ __all__ = [
     'ContextCancelled',
     'ModuleNotExposed',
     'MsgStream',
-    'MultiError',
+    'BaseExceptionGroup',
     'Portal',
-    'ReceiveMsgStream',
     'RemoteActorError',
     'breakpoint',
     'context',

tractor/_clustering.py

@@ -32,9 +32,12 @@ import tractor
 async def open_actor_cluster(
     modules: list[str],
     count: int = cpu_count(),
-    names: Optional[list[str]] = None,
-    start_method: Optional[str] = None,
+    names: list[str] | None = None,
     hard_kill: bool = False,
+
+    # passed through verbatim to ``open_root_actor()``
+    **runtime_kwargs,
+
 ) -> AsyncGenerator[
     dict[str, tractor.Portal],
     None,
@@ -49,7 +52,9 @@ async def open_actor_cluster(
         raise ValueError(
             'Number of names is {len(names)} but count it {count}')
 
-    async with tractor.open_nursery(start_method=start_method) as an:
+    async with tractor.open_nursery(
+        **runtime_kwargs,
+    ) as an:
         async with trio.open_nursery() as n:
             uid = tractor.current_actor().uid
 

tractor/_debug.py

@@ -20,11 +20,16 @@ Multi-core debugging for da peeps!
 """
 from __future__ import annotations
 import bdb
+import os
 import sys
 import signal
-from functools import partial
+from functools import (
+    partial,
+    cached_property,
+)
 from contextlib import asynccontextmanager as acm
 from typing import (
+    Any,
     Optional,
     Callable,
     AsyncIterator,
@@ -32,27 +37,23 @@ from typing import (
 )
 from types import FrameType
 
+import pdbp
 import tractor
 import trio
 from trio_typing import TaskStatus
 
 from .log import get_logger
 from ._discovery import get_root
-from ._state import is_root_process, debug_mode
-from ._exceptions import is_multi_cancelled
+from ._state import (
+    is_root_process,
+    debug_mode,
+)
+from ._exceptions import (
+    is_multi_cancelled,
+    ContextCancelled,
+)
 from ._ipc import Channel
 
-
-try:
-    # wtf: only exported when installed in dev mode?
-    import pdbpp
-except ImportError:
-    # pdbpp is installed in regular mode...it monkey patches stuff
-    import pdb
-    xpm = getattr(pdb, 'xpm', None)
-    assert xpm, "pdbpp is not installed?"  # type: ignore
-    pdbpp = pdb
-
 log = get_logger(__name__)
 
 
@@ -66,11 +67,28 @@ class Lock:
     Mostly to avoid a lot of ``global`` declarations for now XD.
 
     '''
+    repl: MultiActorPdb | None = None
     # placeholder for function to set a ``trio.Event`` on debugger exit
     # pdb_release_hook: Optional[Callable] = None
 
+    _trio_handler: Callable[
+        [int, Optional[FrameType]], Any
+    ] | int | None = None
+
     # actor-wide variable pointing to current task name using debugger
-    local_task_in_debug: Optional[str] = None
+    local_task_in_debug: str | None = None
+
+    # NOTE: set by the current task waiting on the root tty lock from
+    # the CALLER side of the `lock_tty_for_child()` context entry-call
+    # and must be cancelled if this actor is cancelled via IPC
+    # request-message otherwise deadlocks with the parent actor may
+    # ensure
+    _debugger_request_cs: Optional[trio.CancelScope] = None
+
+    # NOTE: set only in the root actor for the **local** root spawned task
+    # which has acquired the lock (i.e. this is on the callee side of
+    # the `lock_tty_for_child()` context entry).
+    _root_local_task_cs_in_debug: Optional[trio.CancelScope] = None
 
     # actor tree-wide actor uid that supposedly has the tty lock
     global_actor_in_debug: Optional[tuple[str, str]] = None
@@ -81,29 +99,22 @@ class Lock:
     # lock in root actor preventing multi-access to local tty
     _debug_lock: trio.StrictFIFOLock = trio.StrictFIFOLock()
 
-    # XXX: set by the current task waiting on the root tty lock
-    # and must be cancelled if this actor is cancelled via message
-    # otherwise deadlocks with the parent actor may ensure
-    _debugger_request_cs: Optional[trio.CancelScope] = None
-
     _orig_sigint_handler: Optional[Callable] = None
+    _blocked: set[tuple[str, str]] = set()
 
     @classmethod
     def shield_sigint(cls):
         cls._orig_sigint_handler = signal.signal(
             signal.SIGINT,
-                shield_sigint,
+            shield_sigint_handler,
         )
 
     @classmethod
     def unshield_sigint(cls):
-        if cls._orig_sigint_handler is not None:
-            # restore original sigint handler
-            signal.signal(
-                signal.SIGINT,
-                cls._orig_sigint_handler
-            )
-
+        # always restore ``trio``'s sigint handler. see notes below in
+        # the pdb factory about the nightmare that is that code swapping
+        # out the handler when the repl activates...
+        signal.signal(signal.SIGINT, cls._trio_handler)
         cls._orig_sigint_handler = None
 
     @classmethod
@@ -130,24 +141,29 @@ class Lock:
         finally:
             # restore original sigint handler
             cls.unshield_sigint()
+            cls.repl = None
 
 
-class TractorConfig(pdbpp.DefaultConfig):
+class TractorConfig(pdbp.DefaultConfig):
     '''
-    Custom ``pdbpp`` goodness.
+    Custom ``pdbp`` goodness :surfer:
 
     '''
-    # use_pygments = True
-    # sticky_by_default = True
-    enable_hidden_frames = False
+    use_pygments: bool = True
+    sticky_by_default: bool = False
+    enable_hidden_frames: bool = False
+
+    # much thanks @mdmintz for the hot tip!
+    # fixes line spacing issue when resizing terminal B)
+    truncate_long_lines: bool = False
 
 
-class MultiActorPdb(pdbpp.Pdb):
+class MultiActorPdb(pdbp.Pdb):
     '''
-    Add teardown hooks to the regular ``pdbpp.Pdb``.
+    Add teardown hooks to the regular ``pdbp.Pdb``.
 
     '''
-    # override the pdbpp config with our coolio one
+    # override the pdbp config with our coolio one
     DefaultConfig = TractorConfig
 
     # def preloop(self):
@@ -168,6 +184,35 @@ class MultiActorPdb(pdbpp.Pdb):
         finally:
             Lock.release()
 
+    # XXX NOTE: we only override this because apparently the stdlib pdb
+    # bois likes to touch the SIGINT handler as much as i like to touch
+    # my d$%&.
+    def _cmdloop(self):
+        self.cmdloop()
+
+    @cached_property
+    def shname(self) -> str | None:
+        '''
+        Attempt to return the login shell name with a special check for
+        the infamous `xonsh` since it seems to have some issues much
+        different from std shells when it comes to flushing the prompt?
+
+        '''
+        # SUPER HACKY and only really works if `xonsh` is not used
+        # before spawning further sub-shells..
+        shpath = os.getenv('SHELL', None)
+
+        if shpath:
+            if (
+                os.getenv('XONSH_LOGIN', default=False)
+                or 'xonsh' in shpath
+            ):
+                return 'xonsh'
+
+            return os.path.basename(shpath)
+
+        return None
+
 
 @acm
 async def _acquire_debug_lock_from_root_task(
@@ -196,6 +241,12 @@ async def _acquire_debug_lock_from_root_task(
             f"entering lock checkpoint, remote task: {task_name}:{uid}"
         )
         we_acquired = True
+
+        # NOTE: if the surrounding cancel scope from the
+        # `lock_tty_for_child()` caller is cancelled, this line should
+        # unblock and NOT leave us in some kind of
+        # a "child-locked-TTY-but-child-is-uncontactable-over-IPC"
+        # condition.
         await Lock._debug_lock.acquire()
 
         if Lock.no_remote_has_tty is None:
@@ -256,7 +307,7 @@ async def lock_tty_for_child(
 ) -> str:
     '''
     Lock the TTY in the root process of an actor tree in a new
-    inter-actor-context-task such that the ``pdbpp`` debugger console
+    inter-actor-context-task such that the ``pdbp`` debugger console
     can be mutex-allocated to the calling sub-actor for REPL control
     without interference by other processes / threads.
 
@@ -267,6 +318,15 @@ async def lock_tty_for_child(
     '''
     task_name = trio.lowlevel.current_task().name
 
+    if tuple(subactor_uid) in Lock._blocked:
+        log.warning(
+            f'Actor {subactor_uid} is blocked from acquiring debug lock\n'
+            f"remote task: {task_name}:{subactor_uid}"
+        )
+        ctx._enter_debugger_on_cancel = False
+        await ctx.cancel(f'Debug lock blocked for {subactor_uid}')
+        return 'pdb_lock_blocked'
+
     # TODO: when we get to true remote debugging
     # this will deliver stdin data?
 
@@ -280,8 +340,9 @@ async def lock_tty_for_child(
 
     try:
         with (
-            trio.CancelScope(shield=True),
+            trio.CancelScope(shield=True) as debug_lock_cs,
         ):
+            Lock._root_local_task_cs_in_debug = debug_lock_cs
             async with _acquire_debug_lock_from_root_task(subactor_uid):
 
                 # indicate to child that we've locked stdio
@@ -297,6 +358,7 @@ async def lock_tty_for_child(
         return "pdb_unlock_complete"
 
     finally:
+        Lock._root_local_task_cs_in_debug = None
         Lock.unshield_sigint()
 
 
@@ -332,7 +394,7 @@ async def wait_for_parent_stdin_hijack(
 
                 ) as (ctx, val):
 
-                    log.pdb('locked context')
+                    log.debug('locked context')
                     assert val == 'Locked'
 
                     async with ctx.open_stream() as stream:
@@ -351,21 +413,21 @@ async def wait_for_parent_stdin_hijack(
                         # sync with callee termination
                         assert await ctx.result() == "pdb_unlock_complete"
 
-                log.pdb('unlocked context')
+                log.debug('exitting child side locking task context')
 
-        except tractor.ContextCancelled:
+        except ContextCancelled:
             log.warning('Root actor cancelled debug lock')
+            raise
 
         finally:
-            log.pdb(f"Exiting debugger for actor {actor_uid}")
             Lock.local_task_in_debug = None
-            log.pdb(f"Child {actor_uid} released parent stdio lock")
+            log.debug('Exiting debugger from child')
 
 
 def mk_mpdb() -> tuple[MultiActorPdb, Callable]:
 
     pdb = MultiActorPdb()
-    # signal.signal = pdbpp.hideframe(signal.signal)
+    # signal.signal = pdbp.hideframe(signal.signal)
 
     Lock.shield_sigint()
 
@@ -392,9 +454,8 @@ async def _breakpoint(
 
     '''
     __tracebackhide__ = True
-
-    pdb, undo_sigint = mk_mpdb()
     actor = tractor.current_actor()
+    pdb, undo_sigint = mk_mpdb()
     task_name = trio.lowlevel.current_task().name
 
     # TODO: is it possible to debug a trio.Cancelled except block?
@@ -404,7 +465,10 @@ async def _breakpoint(
     # with trio.CancelScope(shield=shield):
     #     await trio.lowlevel.checkpoint()
 
-    if not Lock.local_pdb_complete or Lock.local_pdb_complete.is_set():
+    if (
+        not Lock.local_pdb_complete
+        or Lock.local_pdb_complete.is_set()
+    ):
         Lock.local_pdb_complete = trio.Event()
 
     # TODO: need a more robust check for the "root" actor
@@ -418,7 +482,10 @@ async def _breakpoint(
             # Recurrence entry case: this task already has the lock and
             # is likely recurrently entering a breakpoint
             if Lock.local_task_in_debug == task_name:
-                # noop on recurrent entry case
+                # noop on recurrent entry case but we want to trigger
+                # a checkpoint to allow other actors error-propagate and
+                # potetially avoid infinite re-entries in some subactor.
+                await trio.lowlevel.checkpoint()
                 return
 
             # if **this** actor is already in debug mode block here
@@ -437,18 +504,29 @@ async def _breakpoint(
         # root nursery so that the debugger can continue to run without
         # being restricted by the scope of a new task nursery.
 
-        # NOTE: if we want to debug a trio.Cancelled triggered exception
+        # TODO: if we want to debug a trio.Cancelled triggered exception
         # we have to figure out how to avoid having the service nursery
-        # cancel on this task start? I *think* this works below?
+        # cancel on this task start? I *think* this works below:
+        # ```python
         #   actor._service_n.cancel_scope.shield = shield
+        # ```
+        # but not entirely sure if that's a sane way to implement it?
         try:
             with trio.CancelScope(shield=True):
                 await actor._service_n.start(
                     wait_for_parent_stdin_hijack,
                     actor.uid,
                 )
+                Lock.repl = pdb
         except RuntimeError:
             Lock.release()
+
+            if actor._cancel_called:
+                # service nursery won't be usable and we
+                # don't want to lock up the root either way since
+                # we're in (the midst of) cancellation.
+                return
+
             raise
 
     elif is_root_process():
@@ -478,6 +556,7 @@ async def _breakpoint(
 
         Lock.global_actor_in_debug = actor.uid
         Lock.local_task_in_debug = task_name
+        Lock.repl = pdb
 
     try:
         # block here one (at the appropriate frame *up*) where
@@ -498,22 +577,18 @@ async def _breakpoint(
     #     # frame = sys._getframe()
     #     # last_f = frame.f_back
     #     # last_f.f_globals['__tracebackhide__'] = True
-    #     # signal.signal = pdbpp.hideframe(signal.signal)
-    #     signal.signal(
-    #         signal.SIGINT,
-    #         orig_handler
-    #     )
+    #     # signal.signal = pdbp.hideframe(signal.signal)
 
 
-def shield_sigint(
+def shield_sigint_handler(
     signum: int,
     frame: 'frame',  # type: ignore # noqa
-    pdb_obj: Optional[MultiActorPdb] = None,
+    # pdb_obj: Optional[MultiActorPdb] = None,
     *args,
 
 ) -> None:
     '''
-    Specialized debugger compatible SIGINT handler.
+    Specialized, debugger-aware SIGINT handler.
 
     In childred we always ignore to avoid deadlocks since cancellation
     should always be managed by the parent supervising actor. The root
@@ -525,6 +600,7 @@ def shield_sigint(
     uid_in_debug = Lock.global_actor_in_debug
 
     actor = tractor.current_actor()
+    # print(f'{actor.uid} in HANDLER with ')
 
     def do_cancel():
         # If we haven't tried to cancel the runtime then do that instead
@@ -558,6 +634,9 @@ def shield_sigint(
                 )
                 return do_cancel()
 
+    # only set in the actor actually running the REPL
+    pdb_obj = Lock.repl
+
     # root actor branch that reports whether or not a child
     # has locked debugger.
     if (
@@ -570,16 +649,36 @@ def shield_sigint(
         # which has already terminated to unlock.
         and any_connected
     ):
+        # we are root and some actor is in debug mode
+        # if uid_in_debug is not None:
+
+        if pdb_obj:
             name = uid_in_debug[0]
             if name != 'root':
                 log.pdb(
-                f"Ignoring SIGINT while child in debug mode: `{uid_in_debug}`"
+                    f"Ignoring SIGINT, child in debug mode: `{uid_in_debug}`"
                 )
 
             else:
                 log.pdb(
                     "Ignoring SIGINT while in debug mode"
                 )
+    elif (
+        is_root_process()
+    ):
+        if pdb_obj:
+            log.pdb(
+                "Ignoring SIGINT since debug mode is enabled"
+            )
+
+        if (
+            Lock._root_local_task_cs_in_debug
+            and not Lock._root_local_task_cs_in_debug.cancel_called
+        ):
+            Lock._root_local_task_cs_in_debug.cancel()
+
+            # revert back to ``trio`` handler asap!
+            Lock.unshield_sigint()
 
     # child actor that has locked the debugger
     elif not is_root_process():
@@ -595,7 +694,10 @@ def shield_sigint(
             return do_cancel()
 
         task = Lock.local_task_in_debug
-        if task:
+        if (
+            task
+            and pdb_obj
+        ):
             log.pdb(
                 f"Ignoring SIGINT while task in debug mode: `{task}`"
             )
@@ -605,20 +707,26 @@ def shield_sigint(
         # https://github.com/goodboy/tractor/issues/320
         # elif debug_mode():
 
-    else:
-        log.pdb(
-            "Ignoring SIGINT since debug mode is enabled"
-        )
+    else:  # XXX: shouldn't ever get here?
+        print("WTFWTFWTF")
+        raise KeyboardInterrupt
 
     # NOTE: currently (at least on ``fancycompleter`` 0.9.2)
-    # it lookks to be that the last command that was run (eg. ll)
+    # it looks to be that the last command that was run (eg. ll)
     # will be repeated by default.
 
-    # TODO: maybe redraw/print last REPL output to console
+    # maybe redraw/print last REPL output to console since
+    # we want to alert the user that more input is expect since
+    # nothing has been done dur to ignoring sigint.
     if (
-        pdb_obj
-        and sys.version_info <= (3, 10)
+        pdb_obj  # only when this actor has a REPL engaged
     ):
+        # XXX: yah, mega hack, but how else do we catch this madness XD
+        if pdb_obj.shname == 'xonsh':
+            pdb_obj.stdout.write(pdb_obj.prompt)
+
+        pdb_obj.stdout.flush()
+
         # TODO: make this work like sticky mode where if there is output
         # detected as written to the tty we redraw this part underneath
         # and erase the past draw of this same bit above?
@@ -629,21 +737,13 @@ def shield_sigint(
         # https://github.com/goodboy/tractor/issues/130#issuecomment-663752040
         # https://github.com/prompt-toolkit/python-prompt-toolkit/blob/c2c6af8a0308f9e5d7c0e28cb8a02963fe0ce07a/prompt_toolkit/patch_stdout.py
 
-        # XXX: lol, see ``pdbpp`` issue:
+        # XXX LEGACY: lol, see ``pdbpp`` issue:
         # https://github.com/pdbpp/pdbpp/issues/496
 
-        # TODO: pretty sure this is what we should expect to have to run
-        # in total but for now we're just going to wait until `pdbpp`
-        # figures out it's own stuff on 3.10 (and maybe we'll help).
-        # pdb_obj.do_longlist(None)
-
-        # XXX: we were doing this but it shouldn't be required..
-        print(pdb_obj.prompt, end='', flush=True)
-
 
 def _set_trace(
-    actor: Optional[tractor.Actor] = None,
-    pdb: Optional[MultiActorPdb] = None,
+    actor: tractor.Actor | None = None,
+    pdb: MultiActorPdb | None = None,
 ):
     __tracebackhide__ = True
     actor = actor or tractor.current_actor()
@@ -653,7 +753,11 @@ def _set_trace(
     if frame:
         frame = frame.f_back  # type: ignore
 
-    if frame and pdb and actor is not None:
+    if (
+        frame
+        and pdb
+        and actor is not None
+    ):
         log.pdb(f"\nAttaching pdb to actor: {actor.uid}\n")
         # no f!#$&* idea, but when we're in async land
         # we need 2x frames up?
@@ -662,7 +766,8 @@ def _set_trace(
     else:
         pdb, undo_sigint = mk_mpdb()
 
-        # we entered the global ``breakpoint()`` built-in from sync code?
+        # we entered the global ``breakpoint()`` built-in from sync
+        # code?
         Lock.local_task_in_debug = 'sync'
 
     pdb.set_trace(frame=frame)
@@ -692,7 +797,7 @@ def _post_mortem(
     # https://github.com/pdbpp/pdbpp/issues/480
     # TODO: help with a 3.10+ major release if/when it arrives.
 
-    pdbpp.xpm(Pdb=lambda: pdb)
+    pdbp.xpm(Pdb=lambda: pdb)
 
 
 post_mortem = partial(
@@ -721,7 +826,9 @@ async def _maybe_enter_pm(err):
         and not is_multi_cancelled(err)
     ):
         log.debug("Actor crashed, entering debug mode")
+        try:
             await post_mortem()
+        finally:
             Lock.release()
             return True
 
@@ -761,7 +868,10 @@ async def maybe_wait_for_debugger(
 
 ) -> None:
 
-    if not debug_mode() and not child_in_debug:
+    if (
+        not debug_mode()
+        and not child_in_debug
+    ):
         return
 
     if (

tractor/_discovery.py

@@ -108,7 +108,7 @@ async def query_actor(
 @acm
 async def find_actor(
     name: str,
-    arbiter_sockaddr: tuple[str, int] = None
+    arbiter_sockaddr: tuple[str, int] | None = None
 
 ) -> AsyncGenerator[Optional[Portal], None]:
     '''
@@ -134,7 +134,7 @@ async def find_actor(
 @acm
 async def wait_for_actor(
     name: str,
-    arbiter_sockaddr: tuple[str, int] = None
+    arbiter_sockaddr: tuple[str, int] | None = None
 ) -> AsyncGenerator[Portal, None]:
     """Wait on an actor to register with the arbiter.
 

tractor/_entry.py

@@ -18,15 +18,28 @@
 Sub-process entry points.
 
 """
+from __future__ import annotations
 from functools import partial
-from typing import Any
+from typing import (
+    Any,
+    TYPE_CHECKING,
+)
 
 import trio  # type: ignore
 
-from .log import get_console_log, get_logger
+from .log import (
+    get_console_log,
+    get_logger,
+)
 from . import _state
 from .to_asyncio import run_as_asyncio_guest
-from ._runtime import async_main, Actor
+from ._runtime import (
+    async_main,
+    Actor,
+)
+
+if TYPE_CHECKING:
+    from ._spawn import SpawnMethodKey
 
 
 log = get_logger(__name__)
@@ -34,11 +47,11 @@ log = get_logger(__name__)
 
 def _mp_main(
 
-    actor: 'Actor',  # type: ignore
+    actor: Actor,  # type: ignore
     accept_addr: tuple[str, int],
     forkserver_info: tuple[Any, Any, Any, Any, Any],
-    start_method: str,
-    parent_addr: tuple[str, int] = None,
+    start_method: SpawnMethodKey,
+    parent_addr: tuple[str, int] | None = None,
     infect_asyncio: bool = False,
 
 ) -> None:
@@ -85,7 +98,7 @@ def _trio_main(
 
     actor: Actor,  # type: ignore
     *,
-    parent_addr: tuple[str, int] = None,
+    parent_addr: tuple[str, int] | None = None,
     infect_asyncio: bool = False,
 
 ) -> None:

tractor/_exceptions.py

@@ -27,6 +27,7 @@ import importlib
 import builtins
 import traceback
 
+import exceptiongroup as eg
 import trio
 
 
@@ -52,9 +53,6 @@ class RemoteActorError(Exception):
         self.type = suberror_type
         self.msgdata = msgdata
 
-    # TODO: a trio.MultiError.catch like context manager
-    # for catching underlying remote errors of a particular type
-
 
 class InternalActorError(RemoteActorError):
     """Remote internal ``tractor`` error indicating
@@ -123,10 +121,12 @@ def unpack_error(
     err_type=RemoteActorError
 
 ) -> Exception:
-    """Unpack an 'error' message from the wire
+    '''
+    Unpack an 'error' message from the wire
     into a local ``RemoteActorError``.
 
-    """
+    '''
+    __tracebackhide__ = True
     error = msg['error']
 
     tb_str = error.get('tb_str', '')
@@ -139,7 +139,12 @@ def unpack_error(
         suberror_type = trio.Cancelled
 
     else:  # try to lookup a suitable local error type
-        for ns in [builtins, _this_mod, trio]:
+        for ns in [
+            builtins,
+            _this_mod,
+            eg,
+            trio,
+        ]:
             try:
                 suberror_type = getattr(ns, type_name)
                 break
@@ -158,12 +163,15 @@ def unpack_error(
 
 
 def is_multi_cancelled(exc: BaseException) -> bool:
-    """Predicate to determine if a ``trio.MultiError`` contains only
-    ``trio.Cancelled`` sub-exceptions (and is likely the result of
+    '''
+    Predicate to determine if a possible ``eg.BaseExceptionGroup`` contains
+    only ``trio.Cancelled`` sub-exceptions (and is likely the result of
     cancelling a collection of subtasks.
 
-    """
-    return not trio.MultiError.filter(
-        lambda exc: exc if not isinstance(exc, trio.Cancelled) else None,
-        exc,
-    )
+    '''
+    if isinstance(exc, eg.BaseExceptionGroup):
+        return exc.subgroup(
+            lambda exc: isinstance(exc, trio.Cancelled)
+        ) is not None
+
+    return False

tractor/_ipc.py

@@ -341,7 +341,7 @@ class Channel:
 
     async def connect(
         self,
-        destaddr: tuple[Any, ...] = None,
+        destaddr: tuple[Any, ...] | None = None,
         **kwargs
 
     ) -> MsgTransport:

tractor/_portal.py

@@ -35,6 +35,7 @@ import warnings
 import trio
 from async_generator import asynccontextmanager
 
+from .trionics import maybe_open_nursery
 from ._state import current_actor
 from ._ipc import Channel
 from .log import get_logger
@@ -44,43 +45,27 @@ from ._exceptions import (
     NoResult,
     ContextCancelled,
 )
-from ._streaming import Context, ReceiveMsgStream
+from ._streaming import (
+    Context,
+    MsgStream,
+)
 
 
 log = get_logger(__name__)
 
 
-@asynccontextmanager
-async def maybe_open_nursery(
-    nursery: trio.Nursery = None,
-    shield: bool = False,
-) -> AsyncGenerator[trio.Nursery, Any]:
-    '''
-    Create a new nursery if None provided.
-
-    Blocks on exit as expected if no input nursery is provided.
-
-    '''
-    if nursery is not None:
-        yield nursery
-    else:
-        async with trio.open_nursery() as nursery:
-            nursery.cancel_scope.shield = shield
-            yield nursery
-
-
 def _unwrap_msg(
-
     msg: dict[str, Any],
     channel: Channel
 
 ) -> Any:
+    __tracebackhide__ = True
     try:
         return msg['return']
     except KeyError:
         # internal error should never get here
         assert msg.get('cid'), "Received internal error at portal?"
-        raise unpack_error(msg, channel)
+        raise unpack_error(msg, channel) from None
 
 
 class MessagingError(Exception):
@@ -119,7 +104,7 @@ class Portal:
         # it is expected that ``result()`` will be awaited at some
         # point.
         self._expect_result: Optional[Context] = None
-        self._streams: set[ReceiveMsgStream] = set()
+        self._streams: set[MsgStream] = set()
         self.actor = current_actor()
 
     async def _submit_for_result(
@@ -154,6 +139,7 @@ class Portal:
         Return the result(s) from the remote actor's "main" task.
 
         '''
+        # __tracebackhide__ = True
         # Check for non-rpc errors slapped on the
         # channel for which we always raise
         exc = self.channel._exc
@@ -203,7 +189,7 @@ class Portal:
 
     async def cancel_actor(
         self,
-        timeout: float = None,
+        timeout: float | None = None,
 
     ) -> bool:
         '''
@@ -333,7 +319,7 @@ class Portal:
         async_gen_func: Callable,  # typing: ignore
         **kwargs,
 
-    ) -> AsyncGenerator[ReceiveMsgStream, None]:
+    ) -> AsyncGenerator[MsgStream, None]:
 
         if not inspect.isasyncgenfunction(async_gen_func):
             if not (
@@ -358,7 +344,7 @@ class Portal:
 
         try:
             # deliver receive only stream
-            async with ReceiveMsgStream(
+            async with MsgStream(
                 ctx, ctx._recv_chan,
             ) as rchan:
                 self._streams.add(rchan)
@@ -478,7 +464,6 @@ class Portal:
             # sure it's worth being pedantic:
             # Exception,
             # trio.Cancelled,
-            # trio.MultiError,
             # KeyboardInterrupt,
 
         ) as err:
@@ -515,6 +500,10 @@ class Portal:
                     f'actor: {uid}'
                 )
                 result = await ctx.result()
+                log.runtime(
+                    f'Context {fn_name} returned '
+                    f'value from callee `{result}`'
+                )
 
             # though it should be impossible for any tasks
             # operating *in* this scope to have survived
@@ -536,12 +525,6 @@ class Portal:
                         f'task:{cid}\n'
                         f'actor:{uid}'
                     )
-            else:
-                log.runtime(
-                    f'Context {fn_name} returned '
-                    f'value from callee `{result}`'
-                )
-
             # XXX: (MEGA IMPORTANT) if this is a root opened process we
             # wait for any immediate child in debug before popping the
             # context from the runtime msg loop otherwise inside
@@ -554,7 +537,10 @@ class Portal:
             await maybe_wait_for_debugger()
 
             # remove the context from runtime tracking
-            self.actor._contexts.pop((self.channel.uid, ctx.cid))
+            self.actor._contexts.pop(
+                (self.channel.uid, ctx.cid),
+                None,
+            )
 
 
 @dataclass

tractor/_root.py

@@ -22,16 +22,21 @@ from contextlib import asynccontextmanager
 from functools import partial
 import importlib
 import logging
+import signal
+import sys
 import os
-from typing import (
-    Optional,
-)
 import typing
 import warnings
 
+
+from exceptiongroup import BaseExceptionGroup
 import trio
 
-from ._runtime import Actor, Arbiter, async_main
+from ._runtime import (
+    Actor,
+    Arbiter,
+    async_main,
+)
 from . import _debug
 from . import _spawn
 from . import _state
@@ -51,37 +56,45 @@ logger = log.get_logger('tractor')
 @asynccontextmanager
 async def open_root_actor(
 
+    *,
     # defaults are above
-    arbiter_addr: Optional[tuple[str, int]] = (
-        _default_arbiter_host,
-        _default_arbiter_port,
-    ),
+    arbiter_addr: tuple[str, int] | None = None,
 
-    name: Optional[str] = 'root',
+    # defaults are above
+    registry_addr: tuple[str, int] | None = None,
+
+    name: str | None = 'root',
 
     # either the `multiprocessing` start method:
     # https://docs.python.org/3/library/multiprocessing.html#contexts-and-start-methods
     # OR `trio` (the new default).
-    start_method: Optional[str] = None,
+    start_method: _spawn.SpawnMethodKey | None = None,
 
     # enables the multi-process debugger support
     debug_mode: bool = False,
 
     # internal logging
-    loglevel: Optional[str] = None,
+    loglevel: str | None = None,
 
-    enable_modules: Optional[list] = None,
-    rpc_module_paths: Optional[list] = None,
+    enable_modules: list | None = None,
+    rpc_module_paths: list | None = None,
 
 ) -> typing.Any:
-    """Async entry point for ``tractor``.
+    '''
+    Runtime init entry point for ``tractor``.
 
-    """
+    '''
     # Override the global debugger hook to make it play nice with
-    # ``trio``, see:
+    # ``trio``, see much discussion in:
     # https://github.com/python-trio/trio/issues/1155#issuecomment-742964018
+    builtin_bp_handler = sys.breakpointhook
+    orig_bp_path: str | None = os.environ.get('PYTHONBREAKPOINT', None)
     os.environ['PYTHONBREAKPOINT'] = 'tractor._debug._set_trace'
 
+    # attempt to retreive ``trio``'s sigint handler and stash it
+    # on our debugger lock state.
+    _debug.Lock._trio_handler = signal.getsignal(signal.SIGINT)
+
     # mark top most level process as root actor
     _state._runtime_vars['_is_root'] = True
 
@@ -100,10 +113,22 @@ async def open_root_actor(
     if start_method is not None:
         _spawn.try_set_start_method(start_method)
 
-    arbiter_addr = (host, port) = arbiter_addr or (
+    if arbiter_addr is not None:
+        warnings.warn(
+            '`arbiter_addr` is now deprecated and has been renamed to'
+            '`registry_addr`.\nUse that instead..',
+            DeprecationWarning,
+            stacklevel=2,
+        )
+
+    registry_addr = (host, port) = (
+        registry_addr
+        or arbiter_addr
+        or (
             _default_arbiter_host,
             _default_arbiter_port,
         )
+    )
 
     loglevel = (loglevel or log._default_loglevel).upper()
 
@@ -148,7 +173,7 @@ async def open_root_actor(
 
     except OSError:
         # TODO: make this a "discovery" log level?
-        logger.warning(f"No actor could be found @ {host}:{port}")
+        logger.warning(f"No actor registry found @ {host}:{port}")
 
     # create a local actor and start up its main routine/task
     if arbiter_found:
@@ -158,7 +183,7 @@ async def open_root_actor(
 
         actor = Actor(
             name or 'anonymous',
-            arbiter_addr=arbiter_addr,
+            arbiter_addr=registry_addr,
             loglevel=loglevel,
             enable_modules=enable_modules,
         )
@@ -174,7 +199,7 @@ async def open_root_actor(
 
         actor = Arbiter(
             name or 'arbiter',
-            arbiter_addr=arbiter_addr,
+            arbiter_addr=registry_addr,
             loglevel=loglevel,
             enable_modules=enable_modules,
         )
@@ -205,7 +230,10 @@ async def open_root_actor(
             try:
                 yield actor
 
-            except (Exception, trio.MultiError) as err:
+            except (
+                Exception,
+                BaseExceptionGroup,
+            ) as err:
 
                 entered = await _debug._maybe_enter_pm(err)
 
@@ -229,6 +257,15 @@ async def open_root_actor(
                 await actor.cancel()
     finally:
         _state._current_actor = None
+
+        # restore breakpoint hook state
+        sys.breakpointhook = builtin_bp_handler
+        if orig_bp_path is not None:
+            os.environ['PYTHONBREAKPOINT'] = orig_bp_path
+        else:
+            # clear env back to having no entry
+            os.environ.pop('PYTHONBREAKPOINT')
+
         logger.runtime("Root actor terminated")
 
 
@@ -236,13 +273,13 @@ def run_daemon(
     enable_modules: list[str],
 
     # runtime kwargs
-    name: Optional[str] = 'root',
-    arbiter_addr: tuple[str, int] = (
+    name: str | None = 'root',
+    registry_addr: tuple[str, int] = (
         _default_arbiter_host,
         _default_arbiter_port,
     ),
 
-    start_method: Optional[str] = None,
+    start_method: str | None = None,
     debug_mode: bool = False,
     **kwargs
 
@@ -264,7 +301,7 @@ def run_daemon(
     async def _main():
 
         async with open_root_actor(
-            arbiter_addr=arbiter_addr,
+            registry_addr=registry_addr,
             name=name,
             start_method=start_method,
             debug_mode=debug_mode,

tractor/_runtime.py

@@ -25,21 +25,23 @@ from itertools import chain
 import importlib
 import importlib.util
 import inspect
-import uuid
+import signal
+import sys
 from typing import (
     Any, Optional,
     Union, TYPE_CHECKING,
     Callable,
 )
+import uuid
 from types import ModuleType
-import sys
 import os
 from contextlib import ExitStack
 import warnings
 
+from async_generator import aclosing
+from exceptiongroup import BaseExceptionGroup
 import trio  # type: ignore
 from trio_typing import TaskStatus
-from async_generator import aclosing
 
 from ._ipc import Channel
 from ._streaming import Context
@@ -194,7 +196,7 @@ async def _invoke(
                     res = await coro
                     await chan.send({'return': res, 'cid': cid})
 
-            except trio.MultiError:
+            except BaseExceptionGroup:
                 # if a context error was set then likely
                 # thei multierror was raised due to that
                 if ctx._error is not None:
@@ -226,14 +228,17 @@ async def _invoke(
 
                 fname = func.__name__
                 if ctx._cancel_called:
-                    msg = f'{fname} cancelled itself'
+                    msg = f'`{fname}()` cancelled itself'
 
                 elif cs.cancel_called:
                     msg = (
-                        f'{fname} was remotely cancelled by its caller '
+                        f'`{fname}()` was remotely cancelled by its caller '
                         f'{ctx.chan.uid}'
                     )
 
+                if ctx._cancel_msg:
+                    msg += f' with msg:\n{ctx._cancel_msg}'
+
                 # task-contex was cancelled so relay to the cancel to caller
                 raise ContextCancelled(
                     msg,
@@ -263,7 +268,7 @@ async def _invoke(
 
     except (
         Exception,
-        trio.MultiError
+        BaseExceptionGroup,
     ) as err:
 
         if not is_multi_cancelled(err):
@@ -275,8 +280,16 @@ async def _invoke(
             # if not is_multi_cancelled(err) and (
 
             entered_debug: bool = False
-            if not isinstance(err, ContextCancelled) or (
-                isinstance(err, ContextCancelled) and ctx._cancel_called
+            if (
+                not isinstance(err, ContextCancelled)
+                or (
+                    isinstance(err, ContextCancelled)
+                    and ctx._cancel_called
+
+                    # if the root blocks the debugger lock request from a child
+                    # we will get a remote-cancelled condition.
+                    and ctx._enter_debugger_on_cancel
+                )
             ):
                 # XXX: is there any case where we'll want to debug IPC
                 # disconnects as a default?
@@ -286,7 +299,6 @@ async def _invoke(
                 # recovery logic - the only case is some kind of strange bug
                 # in our transport layer itself? Going to keep this
                 # open ended for now.
-
                 entered_debug = await _debug._maybe_enter_pm(err)
 
                 if not entered_debug:
@@ -307,7 +319,7 @@ async def _invoke(
             BrokenPipeError,
         ):
             # if we can't propagate the error that's a big boo boo
-            log.error(
+            log.exception(
                 f"Failed to ship error to caller @ {chan.uid} !?"
             )
 
@@ -339,7 +351,7 @@ def _get_mod_abspath(module):
 
 async def try_ship_error_to_parent(
     channel: Channel,
-    err: Union[Exception, trio.MultiError],
+    err: Union[Exception, BaseExceptionGroup],
 
 ) -> None:
     with trio.CancelScope(shield=True):
@@ -411,8 +423,8 @@ class Actor:
         name: str,
         *,
         enable_modules: list[str] = [],
-        uid: str = None,
-        loglevel: str = None,
+        uid: str | None = None,
+        loglevel: str | None = None,
         arbiter_addr: Optional[tuple[str, int]] = None,
         spawn_method: Optional[str] = None
     ) -> None:
@@ -443,7 +455,7 @@ class Actor:
         self._mods: dict[str, ModuleType] = {}
         self.loglevel = loglevel
 
-        self._arb_addr = (
+        self._arb_addr: tuple[str, int] | None = (
             str(arbiter_addr[0]),
             int(arbiter_addr[1])
         ) if arbiter_addr else None
@@ -476,7 +488,10 @@ class Actor:
         self._parent_chan: Optional[Channel] = None
         self._forkserver_info: Optional[
             tuple[Any, Any, Any, Any, Any]] = None
-        self._actoruid2nursery: dict[Optional[tuple[str, str]], 'ActorNursery'] = {}  # type: ignore  # noqa
+        self._actoruid2nursery: dict[
+            tuple[str, str],
+            ActorNursery | None,
+        ] = {}  # type: ignore  # noqa
 
     async def wait_for_peer(
         self, uid: tuple[str, str]
@@ -698,18 +713,38 @@ class Actor:
                 log.runtime(f"No more channels for {chan.uid}")
                 self._peers.pop(uid, None)
 
-                # for (uid, cid) in self._contexts.copy():
-                #     if chan.uid == uid:
-                #         self._contexts.pop((uid, cid))
-
             log.runtime(f"Peers is {self._peers}")
 
             # No more channels to other actors (at all) registered
             # as connected.
             if not self._peers:
-                log.runtime("Signalling no more peer channels")
+                log.runtime("Signalling no more peer channel connections")
                 self._no_more_peers.set()
 
+                # NOTE: block this actor from acquiring the
+                # debugger-TTY-lock since we have no way to know if we
+                # cancelled it and further there is no way to ensure the
+                # lock will be released if acquired due to having no
+                # more active IPC channels.
+                if _state.is_root_process():
+                    pdb_lock = _debug.Lock
+                    pdb_lock._blocked.add(uid)
+                    log.runtime(f"{uid} blocked from pdb locking")
+
+                    # if a now stale local task has the TTY lock still
+                    # we cancel it to allow servicing other requests for
+                    # the lock.
+                    db_cs = pdb_lock._root_local_task_cs_in_debug
+                    if (
+                        db_cs
+                        and not db_cs.cancel_called
+                    ):
+                        log.warning(
+                            f'STALE DEBUG LOCK DETECTED FOR {uid}'
+                        )
+                        # TODO: figure out why this breaks tests..
+                        db_cs.cancel()
+
             # XXX: is this necessary (GC should do it)?
             if chan.connected():
                 # if the channel is still connected it may mean the far
@@ -794,7 +829,12 @@ class Actor:
 
             if ctx._backpressure:
                 log.warning(text)
+                try:
                     await send_chan.send(msg)
+                except trio.BrokenResourceError:
+                    # XXX: local consumer has closed their side
+                    # so cancel the far end streaming task
+                    log.warning(f"{chan} is already closed")
             else:
                 try:
                     raise StreamOverrun(text) from None
@@ -948,7 +988,7 @@ class Actor:
         handler_nursery: trio.Nursery,
         *,
         # (host, port) to bind for channel server
-        accept_host: tuple[str, int] = None,
+        accept_host: tuple[str, int] | None = None,
         accept_port: int = 0,
         task_status: TaskStatus[trio.Nursery] = trio.TASK_STATUS_IGNORED,
     ) -> None:
@@ -1199,6 +1239,10 @@ async def async_main(
     and when cancelled effectively cancels the actor.
 
     '''
+    # attempt to retreive ``trio``'s sigint handler and stash it
+    # on our debugger lock state.
+    _debug.Lock._trio_handler = signal.getsignal(signal.SIGINT)
+
     registered_with_arbiter = False
     try:
 
@@ -1335,10 +1379,12 @@ async def async_main(
         actor.lifetime_stack.close()
 
         # Unregister actor from the arbiter
-        if registered_with_arbiter and (
-                actor._arb_addr is not None
+        if (
+            registered_with_arbiter
+            and not actor.is_arbiter
         ):
             failed = False
+            assert isinstance(actor._arb_addr, tuple)
             with trio.move_on_after(0.5) as cs:
                 cs.shield = True
                 try:
@@ -1520,7 +1566,10 @@ async def process_messages(
                         partial(_invoke, actor, cid, chan, func, kwargs),
                         name=funcname,
                     )
-                except (RuntimeError, trio.MultiError):
+                except (
+                    RuntimeError,
+                    BaseExceptionGroup,
+                ):
                     # avoid reporting a benign race condition
                     # during actor runtime teardown.
                     nursery_cancelled_before_task = True
@@ -1560,12 +1609,18 @@ async def process_messages(
         # handshake for them (yet) and instead we simply bail out of
         # the message loop and expect the teardown sequence to clean
         # up.
-        log.runtime(f'channel from {chan.uid} closed abruptly:\n{chan}')
+        log.runtime(
+            f'channel from {chan.uid} closed abruptly:\n'
+            f'-> {chan.raddr}\n'
+        )
 
         # transport **was** disconnected
         return True
 
-    except (Exception, trio.MultiError) as err:
+    except (
+        Exception,
+        BaseExceptionGroup,
+    ) as err:
         if nursery_cancelled_before_task:
             sn = actor._service_n
             assert sn and sn.cancel_scope.cancel_called
@@ -1606,17 +1661,28 @@ class Arbiter(Actor):
     '''
     is_arbiter = True
 
-    def __init__(self, *args, **kwargs):
+    def __init__(self, *args, **kwargs) -> None:
 
         self._registry: dict[
             tuple[str, str],
             tuple[str, int],
         ] = {}
-        self._waiters = {}
+        self._waiters: dict[
+            str,
+            # either an event to sync to receiving an actor uid (which
+            # is filled in once the actor has sucessfully registered),
+            # or that uid after registry is complete.
+            list[trio.Event | tuple[str, str]]
+        ] = {}
 
         super().__init__(*args, **kwargs)
 
-    async def find_actor(self, name: str) -> Optional[tuple[str, int]]:
+    async def find_actor(
+        self,
+        name: str,
+
+    ) -> tuple[str, int] | None:
+
         for uid, sockaddr in self._registry.items():
             if name in uid:
                 return sockaddr
@@ -1651,7 +1717,8 @@ class Arbiter(Actor):
         registered.
 
         '''
-        sockaddrs = []
+        sockaddrs: list[tuple[str, int]] = []
+        sockaddr: tuple[str, int]
 
         for (aname, _), sockaddr in self._registry.items():
             if name == aname:
@@ -1661,7 +1728,9 @@ class Arbiter(Actor):
             waiter = trio.Event()
             self._waiters.setdefault(name, []).append(waiter)
             await waiter.wait()
+
             for uid in self._waiters[name]:
+                if not isinstance(uid, trio.Event):
                     sockaddrs.append(self._registry[uid])
 
         return sockaddrs
@@ -1672,11 +1741,11 @@ class Arbiter(Actor):
         sockaddr: tuple[str, int]
 
     ) -> None:
-        uid = name, uuid = (str(uid[0]), str(uid[1]))
+        uid = name, _ = (str(uid[0]), str(uid[1]))
         self._registry[uid] = (str(sockaddr[0]), int(sockaddr[1]))
 
         # pop and signal all waiter events
-        events = self._waiters.pop(name, ())
+        events = self._waiters.pop(name, [])
         self._waiters.setdefault(name, []).append(uid)
         for event in events:
             if isinstance(event, trio.Event):

tractor/_spawn.py

@@ -22,10 +22,15 @@ from __future__ import annotations
 import sys
 import platform
 from typing import (
-    Any, Optional, Callable, TypeVar, TYPE_CHECKING
+    Any,
+    Awaitable,
+    Literal,
+    Callable,
+    TypeVar,
+    TYPE_CHECKING,
 )
-from collections.abc import Awaitable
 
+from exceptiongroup import BaseExceptionGroup
 import trio
 from trio_typing import TaskStatus
 
@@ -39,7 +44,6 @@ from ._state import (
     is_root_process,
     debug_mode,
 )
-
 from .log import get_logger
 from ._portal import Portal
 from ._runtime import Actor
@@ -48,14 +52,20 @@ from ._exceptions import ActorFailure
 
 
 if TYPE_CHECKING:
+    from ._supervise import ActorNursery
     import multiprocessing as mp
     ProcessType = TypeVar('ProcessType', mp.Process, trio.Process)
 
 log = get_logger('tractor')
 
 # placeholder for an mp start context if so using that backend
-_ctx: Optional[mp.context.BaseContext] = None
-_spawn_method: str = "trio"
+_ctx: mp.context.BaseContext | None = None
+SpawnMethodKey = Literal[
+    'trio',  # supported on all platforms
+    'mp_spawn',
+    'mp_forkserver',  # posix only
+]
+_spawn_method: SpawnMethodKey = 'trio'
 
 
 if platform.system() == 'Windows':
@@ -72,7 +82,10 @@ else:
         await trio.lowlevel.wait_readable(proc.sentinel)
 
 
-def try_set_start_method(name: str) -> Optional[mp.context.BaseContext]:
+def try_set_start_method(
+    key: SpawnMethodKey
+
+) -> mp.context.BaseContext | None:
     '''
     Attempt to set the method for process starting, aka the "actor
     spawning backend".
@@ -87,28 +100,30 @@ def try_set_start_method(name: str) -> Optional[mp.context.BaseContext]:
     global _ctx
     global _spawn_method
 
-    methods = mp.get_all_start_methods()
-    if 'fork' in methods:
+    mp_methods = mp.get_all_start_methods()
+    if 'fork' in mp_methods:
         # forking is incompatible with ``trio``s global task tree
-        methods.remove('fork')
+        mp_methods.remove('fork')
 
-    # supported on all platforms
-    methods += ['trio']
-
-    if name not in methods:
-        raise ValueError(
-            f"Spawn method `{name}` is invalid please choose one of {methods}"
-        )
-    elif name == 'forkserver':
+    match key:
+        case 'mp_forkserver':
             from . import _forkserver_override
             _forkserver_override.override_stdlib()
-        _ctx = mp.get_context(name)
-    elif name == 'trio':
-        _ctx = None
-    else:
-        _ctx = mp.get_context(name)
+            _ctx = mp.get_context('forkserver')
 
-    _spawn_method = name
+        case 'mp_spawn':
+            _ctx = mp.get_context('spawn')
+
+        case 'trio':
+            _ctx = None
+
+        case _:
+            raise ValueError(
+                f'Spawn method `{key}` is invalid!\n'
+                f'Please choose one of {SpawnMethodKey}'
+            )
+
+    _spawn_method = key
     return _ctx
 
 
@@ -124,6 +139,7 @@ async def exhaust_portal(
     If the main task is an async generator do our best to consume
     what's left of it.
     '''
+    __tracebackhide__ = True
     try:
         log.debug(f"Waiting on final result from {actor.uid}")
 
@@ -131,8 +147,11 @@ async def exhaust_portal(
         # always be established and shutdown using a context manager api
         final = await portal.result()
 
-    except (Exception, trio.MultiError) as err:
-        # we reraise in the parent task via a ``trio.MultiError``
+    except (
+        Exception,
+        BaseExceptionGroup,
+    ) as err:
+        # we reraise in the parent task via a ``BaseExceptionGroup``
         return err
     except trio.Cancelled as err:
         # lol, of course we need this too ;P
@@ -160,7 +179,7 @@ async def cancel_on_completion(
     '''
     # if this call errors we store the exception for later
     # in ``errors`` which will be reraised inside
-    # a MultiError and we still send out a cancel request
+    # an exception group and we still send out a cancel request
     result = await exhaust_portal(portal, actor)
     if isinstance(result, Exception):
         errors[actor.uid] = result
@@ -180,16 +199,37 @@ async def cancel_on_completion(
 async def do_hard_kill(
     proc: trio.Process,
     terminate_after: int = 3,
+
 ) -> None:
     # NOTE: this timeout used to do nothing since we were shielding
     # the ``.wait()`` inside ``new_proc()`` which will pretty much
     # never release until the process exits, now it acts as
     # a hard-kill time ultimatum.
+    log.debug(f"Terminating {proc}")
     with trio.move_on_after(terminate_after) as cs:
 
-        # NOTE: This ``__aexit__()`` shields internally.
-        async with proc:  # calls ``trio.Process.aclose()``
-            log.debug(f"Terminating {proc}")
+        # NOTE: code below was copied verbatim from the now deprecated
+        # (in 0.20.0) ``trio._subrocess.Process.aclose()``, orig doc
+        # string:
+        #
+        # Close any pipes we have to the process (both input and output)
+        # and wait for it to exit. If cancelled, kills the process and
+        # waits for it to finish exiting before propagating the
+        # cancellation.
+        with trio.CancelScope(shield=True):
+            if proc.stdin is not None:
+                await proc.stdin.aclose()
+            if proc.stdout is not None:
+                await proc.stdout.aclose()
+            if proc.stderr is not None:
+                await proc.stderr.aclose()
+        try:
+            await proc.wait()
+        finally:
+            if proc.returncode is None:
+                proc.kill()
+                with trio.CancelScope(shield=True):
+                    await proc.wait()
 
     if cs.cancelled_caught:
         # XXX: should pretty much never get here unless we have
@@ -240,16 +280,17 @@ async def soft_wait(
 
             if proc.poll() is None:  # type: ignore
                 log.warning(
-                    f'Process still alive after cancel request:\n{uid}')
+                    'Actor still alive after cancel request:\n'
+                    f'{uid}'
+                )
 
                 n.cancel_scope.cancel()
         raise
 
 
 async def new_proc(
-
     name: str,
-    actor_nursery: 'ActorNursery',  # type: ignore  # noqa
+    actor_nursery: ActorNursery,
     subactor: Actor,
     errors: dict[tuple[str, str], Exception],
 
@@ -263,6 +304,41 @@ async def new_proc(
     infect_asyncio: bool = False,
     task_status: TaskStatus[Portal] = trio.TASK_STATUS_IGNORED
 
+) -> None:
+
+    # lookup backend spawning target
+    target = _methods[_spawn_method]
+
+    # mark the new actor with the global spawn method
+    subactor._spawn_method = _spawn_method
+
+    await target(
+        name,
+        actor_nursery,
+        subactor,
+        errors,
+        bind_addr,
+        parent_addr,
+        _runtime_vars,  # run time vars
+        infect_asyncio=infect_asyncio,
+        task_status=task_status,
+    )
+
+
+async def trio_proc(
+    name: str,
+    actor_nursery: ActorNursery,
+    subactor: Actor,
+    errors: dict[tuple[str, str], Exception],
+
+    # passed through to actor main
+    bind_addr: tuple[str, int],
+    parent_addr: tuple[str, int],
+    _runtime_vars: dict[str, Any],  # serialized and sent to _child
+    *,
+    infect_asyncio: bool = False,
+    task_status: TaskStatus[Portal] = trio.TASK_STATUS_IGNORED
+
 ) -> None:
     '''
     Create a new ``Process`` using a "spawn method" as (configured using
@@ -272,11 +348,6 @@ async def new_proc(
     here is to be considered the core supervision strategy.
 
     '''
-    # mark the new actor with the global spawn method
-    subactor._spawn_method = _spawn_method
-    uid = subactor.uid
-
-    if _spawn_method == 'trio':
     spawn_cmd = [
         sys.executable,
         "-m",
@@ -304,11 +375,11 @@ async def new_proc(
         spawn_cmd.append("--asyncio")
 
     cancelled_during_spawn: bool = False
-        proc: Optional[trio.Process] = None
+    proc: trio.Process | None = None
     try:
         try:
             # TODO: needs ``trio_typing`` patch?
-                proc = await trio.lowlevel.open_process(spawn_cmd)  # type: ignore
+            proc = await trio.lowlevel.open_process(spawn_cmd)
 
             log.runtime(f"Started {proc}")
 
@@ -329,7 +400,7 @@ async def new_proc(
                         await maybe_wait_for_debugger()
 
                     elif proc is not None:
-                            async with acquire_debug_lock(uid):
+                        async with acquire_debug_lock(subactor.uid):
                             # soft wait on the proc to terminate
                             with trio.move_on_after(0.5):
                                 await proc.wait()
@@ -340,7 +411,10 @@ async def new_proc(
 
         portal = Portal(chan)
         actor_nursery._children[subactor.uid] = (
-                subactor, proc, portal)
+            subactor,
+            proc,
+            portal,
+        )
 
         # send additional init params
         await chan.send({
@@ -389,21 +463,28 @@ async def new_proc(
             nursery.cancel_scope.cancel()
 
     finally:
-            # The "hard" reap since no actor zombies are allowed!
-            # XXX: do this **after** cancellation/tearfown to avoid
+        # XXX NOTE XXX: The "hard" reap since no actor zombies are
+        # allowed! Do this **after** cancellation/teardown to avoid
         # killing the process too early.
         if proc:
-                log.cancel(f'Hard reap sequence starting for {uid}')
+            log.cancel(f'Hard reap sequence starting for {subactor.uid}')
             with trio.CancelScope(shield=True):
 
                 # don't clobber an ongoing pdb
                 if cancelled_during_spawn:
                     # Try again to avoid TTY clobbering.
-                        async with acquire_debug_lock(uid):
+                    async with acquire_debug_lock(subactor.uid):
                         with trio.move_on_after(0.5):
                             await proc.wait()
 
                 if is_root_process():
+                    # TODO: solve the following issue where we need
+                    # to do a similar wait like this but in an
+                    # "intermediary" parent actor that itself isn't
+                    # in debug but has a child that is, and we need
+                    # to hold off on relaying SIGINT until that child
+                    # is complete.
+                    # https://github.com/goodboy/tractor/issues/320
                     await maybe_wait_for_debugger(
                         child_in_debug=_runtime_vars.get(
                             '_debug_mode', False),
@@ -422,28 +503,10 @@ async def new_proc(
             # subactor
             actor_nursery._children.pop(subactor.uid)
 
-    else:
-        # `multiprocessing`
-        # async with trio.open_nursery() as nursery:
-        await mp_new_proc(
-            name=name,
-            actor_nursery=actor_nursery,
-            subactor=subactor,
-            errors=errors,
-
-            # passed through to actor main
-            bind_addr=bind_addr,
-            parent_addr=parent_addr,
-            _runtime_vars=_runtime_vars,
-            infect_asyncio=infect_asyncio,
-            task_status=task_status,
-        )
-
-
-async def mp_new_proc(
 
+async def mp_proc(
     name: str,
-    actor_nursery: 'ActorNursery',  # type: ignore  # noqa
+    actor_nursery: ActorNursery,  # type: ignore  # noqa
     subactor: Actor,
     errors: dict[tuple[str, str], Exception],
     # passed through to actor main
@@ -468,6 +531,7 @@ async def mp_new_proc(
     assert _ctx
     start_method = _ctx.get_start_method()
     if start_method == 'forkserver':
+
         from multiprocessing import forkserver  # type: ignore
         # XXX do our hackery on the stdlib to avoid multiple
         # forkservers (one at each subproc layer).
@@ -480,23 +544,24 @@ async def mp_new_proc(
             # forkserver.set_forkserver_preload(enable_modules)
             forkserver.ensure_running()
             fs_info = (
-                fs._forkserver_address,
-                fs._forkserver_alive_fd,
+                fs._forkserver_address,  # type: ignore  # noqa
+                fs._forkserver_alive_fd,  # type: ignore  # noqa
                 getattr(fs, '_forkserver_pid', None),
                 getattr(
                     resource_tracker._resource_tracker, '_pid', None),
                 resource_tracker._resource_tracker._fd,
             )
-        else:
+        else:  # request to forkerserver to fork a new child
             assert curr_actor._forkserver_info
             fs_info = (
-                fs._forkserver_address,
-                fs._forkserver_alive_fd,
-                fs._forkserver_pid,
+                fs._forkserver_address,  # type: ignore  # noqa
+                fs._forkserver_alive_fd,  # type: ignore  # noqa
+                fs._forkserver_pid,  # type: ignore  # noqa
                 resource_tracker._resource_tracker._pid,
                 resource_tracker._resource_tracker._fd,
              ) = curr_actor._forkserver_info
     else:
+        # spawn method
         fs_info = (None, None, None, None, None)
 
     proc: mp.Process = _ctx.Process(  # type: ignore
@@ -505,7 +570,7 @@ async def mp_new_proc(
             subactor,
             bind_addr,
             fs_info,
-            start_method,
+            _spawn_method,
             parent_addr,
             infect_asyncio,
         ),
@@ -599,4 +664,16 @@ async def mp_new_proc(
         log.debug(f"Joined {proc}")
 
         # pop child entry to indicate we are no longer managing subactor
-        subactor, proc, portal = actor_nursery._children.pop(subactor.uid)
+        actor_nursery._children.pop(subactor.uid)
+
+        # TODO: prolly report to ``mypy`` how this causes all sorts of
+        # false errors..
+        # subactor, proc, portal = actor_nursery._children.pop(subactor.uid)
+
+
+# proc spawning backend target map
+_methods: dict[SpawnMethodKey, Callable] = {
+    'trio': trio_proc,
+    'mp_spawn': mp_proc,
+    'mp_forkserver': mp_proc,
+}

tractor/_state.py

@@ -22,7 +22,6 @@ from typing import (
     Optional,
     Any,
 )
-from collections.abc import Mapping
 
 import trio
 
@@ -46,30 +45,6 @@ def current_actor(err_on_no_runtime: bool = True) -> 'Actor':  # type: ignore #
     return _current_actor
 
 
-_conc_name_getters = {
-    'task': trio.lowlevel.current_task,
-    'actor': current_actor
-}
-
-
-class ActorContextInfo(Mapping):
-    "Dyanmic lookup for local actor and task names"
-    _context_keys = ('task', 'actor')
-
-    def __len__(self):
-        return len(self._context_keys)
-
-    def __iter__(self):
-        return iter(self._context_keys)
-
-    def __getitem__(self, key: str) -> str:
-        try:
-            return _conc_name_getters[key]().name  # type: ignore
-        except RuntimeError:
-            # no local actor/task context initialized yet
-            return f'no {key} context'
-
-
 def is_main_process() -> bool:
     """Bool determining if this actor is running in the top-most process.
     """

tractor/_streaming.py

@@ -50,12 +50,13 @@ log = get_logger(__name__)
 # - use __slots__ on ``Context``?
 
 
-class ReceiveMsgStream(trio.abc.ReceiveChannel):
+class MsgStream(trio.abc.Channel):
     '''
-    A IPC message stream for receiving logically sequenced values over
-    an inter-actor ``Channel``. This is the type returned to a local
-    task which entered either ``Portal.open_stream_from()`` or
-    ``Context.open_stream()``.
+    A bidirectional message stream for receiving logically sequenced
+    values over an inter-actor IPC ``Channel``.
+
+    This is the type returned to a local task which entered either
+    ``Portal.open_stream_from()`` or ``Context.open_stream()``.
 
     Termination rules:
 
@@ -97,6 +98,9 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
         if self._eoc:
             raise trio.EndOfChannel
 
+        if self._closed:
+            raise trio.ClosedResourceError('This stream was closed')
+
         try:
             msg = await self._rx_chan.receive()
             return msg['yield']
@@ -110,6 +114,9 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
             # - 'error'
             # possibly just handle msg['stop'] here!
 
+            if self._closed:
+                raise trio.ClosedResourceError('This stream was closed')
+
             if msg.get('stop') or self._eoc:
                 log.debug(f"{self} was stopped at remote end")
 
@@ -189,7 +196,6 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
             return
 
         self._eoc = True
-        self._closed = True
 
         # NOTE: this is super subtle IPC messaging stuff:
         # Relay stop iteration to far end **iff** we're
@@ -206,12 +212,8 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
 
         # In the bidirectional case, `Context.open_stream()` will create
         # the `Actor._cids2qs` entry from a call to
-        # `Actor.get_context()` and will send the stop message in
-        # ``__aexit__()`` on teardown so it **does not** need to be
-        # called here.
-        if not self._ctx._portal:
-            # Only for 2 way streams can we can send stop from the
-            # caller side.
+        # `Actor.get_context()` and will call us here to send the stop
+        # msg in ``__aexit__()`` on teardown.
         try:
             # NOTE: if this call is cancelled we expect this end to
             # handle as though the stop was never sent (though if it
@@ -228,7 +230,14 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
             # the underlying channel may already have been pulled
             # in which case our stop message is meaningless since
             # it can't traverse the transport.
-                log.debug(f'Channel for {self} was already closed')
+            ctx = self._ctx
+            log.warning(
+                f'Stream was already destroyed?\n'
+                f'actor: {ctx.chan.uid}\n'
+                f'ctx id: {ctx.cid}'
+            )
+
+        self._closed = True
 
         # Do we close the local mem chan ``self._rx_chan`` ??!?
 
@@ -271,7 +280,8 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
         self,
 
     ) -> AsyncIterator[BroadcastReceiver]:
-        '''Allocate and return a ``BroadcastReceiver`` which delegates
+        '''
+        Allocate and return a ``BroadcastReceiver`` which delegates
         to this message stream.
 
         This allows multiple local tasks to receive each their own copy
@@ -308,15 +318,15 @@ class ReceiveMsgStream(trio.abc.ReceiveChannel):
         async with self._broadcaster.subscribe() as bstream:
             assert bstream.key != self._broadcaster.key
             assert bstream._recv == self._broadcaster._recv
+
+            # NOTE: we patch on a `.send()` to the bcaster so that the
+            # caller can still conduct 2-way streaming using this
+            # ``bstream`` handle transparently as though it was the msg
+            # stream instance.
+            bstream.send = self.send  # type: ignore
+
             yield bstream
 
-
-class MsgStream(ReceiveMsgStream, trio.abc.Channel):
-    '''
-    Bidirectional message stream for use within an inter-actor actor
-    ``Context```.
-
-    '''
     async def send(
         self,
         data: Any
@@ -371,6 +381,8 @@ class Context:
 
     # status flags
     _cancel_called: bool = False
+    _cancel_msg: Optional[str] = None
+    _enter_debugger_on_cancel: bool = True
     _started_called: bool = False
     _started_received: bool = False
     _stream_opened: bool = False
@@ -452,7 +464,11 @@ class Context:
                 if not self._scope_nursery._closed:  # type: ignore
                     self._scope_nursery.start_soon(raiser)
 
-    async def cancel(self) -> None:
+    async def cancel(
+        self,
+        msg: Optional[str] = None,
+
+    ) -> None:
         '''
         Cancel this inter-actor-task context.
 
@@ -461,6 +477,8 @@ class Context:
 
         '''
         side = 'caller' if self._portal else 'callee'
+        if msg:
+            assert side == 'callee', 'Only callee side can provide cancel msg'
 
         log.cancel(f'Cancelling {side} side of context to {self.chan.uid}')
 
@@ -497,8 +515,10 @@ class Context:
                     log.cancel(
                         "Timed out on cancelling remote task "
                         f"{cid} for {self._portal.channel.uid}")
-        else:
+
         # callee side remote task
+        else:
+            self._cancel_msg = msg
 
             # TODO: should we have an explicit cancel message
             # or is relaying the local `trio.Cancelled` as an
@@ -583,23 +603,23 @@ class Context:
         async with MsgStream(
             ctx=self,
             rx_chan=ctx._recv_chan,
-        ) as rchan:
+        ) as stream:
 
             if self._portal:
-                self._portal._streams.add(rchan)
+                self._portal._streams.add(stream)
 
             try:
                 self._stream_opened = True
 
-                # ensure we aren't cancelled before delivering
-                # the stream
+                # XXX: do we need this?
+                # ensure we aren't cancelled before yielding the stream
                 # await trio.lowlevel.checkpoint()
-                yield rchan
+                yield stream
 
-                # XXX: Make the stream "one-shot use".  On exit, signal
+                # NOTE: Make the stream "one-shot use".  On exit, signal
                 # ``trio.EndOfChannel``/``StopAsyncIteration`` to the
                 # far end.
-                await self.send_stop()
+                await stream.aclose()
 
             finally:
                 if self._portal:

tractor/_supervise.py

@@ -18,6 +18,7 @@
 ``trio`` inspired apis and helpers
 
 """
+from contextlib import asynccontextmanager as acm
 from functools import partial
 import inspect
 from typing import (
@@ -27,8 +28,8 @@ from typing import (
 import typing
 import warnings
 
+from exceptiongroup import BaseExceptionGroup
 import trio
-from async_generator import asynccontextmanager
 
 from ._debug import maybe_wait_for_debugger
 from ._state import current_actor, is_main_process
@@ -82,7 +83,7 @@ class ActorNursery:
         actor: Actor,
         ria_nursery: trio.Nursery,
         da_nursery: trio.Nursery,
-        errors: dict[tuple[str, str], Exception],
+        errors: dict[tuple[str, str], BaseException],
     ) -> None:
         # self.supervisor = supervisor  # TODO
         self._actor: Actor = actor
@@ -90,7 +91,11 @@ class ActorNursery:
         self._da_nursery = da_nursery
         self._children: dict[
             tuple[str, str],
-            tuple[Actor, mp.Process, Optional[Portal]]
+            tuple[
+                Actor,
+                trio.Process | mp.Process,
+                Optional[Portal],
+            ]
         ] = {}
         # portals spawned with ``run_in_actor()`` are
         # cancelled when their "main" result arrives
@@ -106,11 +111,11 @@ class ActorNursery:
         name: str,
         *,
         bind_addr: tuple[str, int] = _default_bind_addr,
-        rpc_module_paths: list[str] = None,
-        enable_modules: list[str] = None,
-        loglevel: str = None,  # set log level per subactor
-        nursery: trio.Nursery = None,
-        debug_mode: Optional[bool] = None,
+        rpc_module_paths: list[str] | None = None,
+        enable_modules: list[str] | None = None,
+        loglevel: str | None = None,  # set log level per subactor
+        nursery: trio.Nursery | None = None,
+        debug_mode: Optional[bool] | None = None,
         infect_asyncio: bool = False,
     ) -> Portal:
         '''
@@ -177,9 +182,9 @@ class ActorNursery:
 
         name: Optional[str] = None,
         bind_addr: tuple[str, int] = _default_bind_addr,
-        rpc_module_paths: Optional[list[str]] = None,
-        enable_modules: list[str] = None,
-        loglevel: str = None,  # set log level per subactor
+        rpc_module_paths: list[str] | None = None,
+        enable_modules: list[str] | None = None,
+        loglevel: str | None = None,  # set log level per subactor
         infect_asyncio: bool = False,
 
         **kwargs,  # explicit args to ``fn``
@@ -290,13 +295,17 @@ class ActorNursery:
         self._join_procs.set()
 
 
-@asynccontextmanager
+@acm
 async def _open_and_supervise_one_cancels_all_nursery(
     actor: Actor,
+
 ) -> typing.AsyncGenerator[ActorNursery, None]:
 
+    # TODO: yay or nay?
+    __tracebackhide__ = True
+
     # the collection of errors retreived from spawned sub-actors
-    errors: dict[tuple[str, str], Exception] = {}
+    errors: dict[tuple[str, str], BaseException] = {}
 
     # This is the outermost level "deamon actor" nursery. It is awaited
     # **after** the below inner "run in actor nursery". This allows for
@@ -329,19 +338,17 @@ async def _open_and_supervise_one_cancels_all_nursery(
                     # after we yield upwards
                     yield anursery
 
+                    # When we didn't error in the caller's scope,
+                    # signal all process-monitor-tasks to conduct
+                    # the "hard join phase".
                     log.runtime(
                         f"Waiting on subactors {anursery._children} "
                         "to complete"
                     )
-
-                    # Last bit before first nursery block ends in the case
-                    # where we didn't error in the caller's scope
-
-                    # signal all process monitor tasks to conduct
-                    # hard join phase.
                     anursery._join_procs.set()
 
-                except BaseException as err:
+                except BaseException as inner_err:
+                    errors[actor.uid] = inner_err
 
                     # If we error in the root but the debugger is
                     # engaged we don't want to prematurely kill (and
@@ -358,19 +365,18 @@ async def _open_and_supervise_one_cancels_all_nursery(
                     # worry more are coming).
                     anursery._join_procs.set()
 
-                    try:
                     # XXX: hypothetically an error could be
                     # raised and then a cancel signal shows up
                     # slightly after in which case the `else:`
                     # block here might not complete?  For now,
                     # shield both.
                     with trio.CancelScope(shield=True):
-                            etype = type(err)
+                        etype = type(inner_err)
                         if etype in (
                             trio.Cancelled,
                             KeyboardInterrupt
                         ) or (
-                                is_multi_cancelled(err)
+                            is_multi_cancelled(inner_err)
                         ):
                             log.cancel(
                                 f"Nursery for {current_actor().uid} "
@@ -378,29 +384,23 @@ async def _open_and_supervise_one_cancels_all_nursery(
                         else:
                             log.exception(
                                 f"Nursery for {current_actor().uid} "
-                                    f"errored with {err}, ")
+                                f"errored with")
 
                         # cancel all subactors
                         await anursery.cancel()
 
-                    except trio.MultiError as merr:
-                        # If we receive additional errors while waiting on
-                        # remaining subactors that were cancelled,
-                        # aggregate those errors with the original error
-                        # that triggered this teardown.
-                        if err not in merr.exceptions:
-                            raise trio.MultiError(merr.exceptions + [err])
-                    else:
-                        raise
-
             # ria_nursery scope end
 
-        # XXX: do we need a `trio.Cancelled` catch here as well?
-        # this is the catch around the ``.run_in_actor()`` nursery
+        # TODO: this is the handler around the ``.run_in_actor()``
+        # nursery. Ideally we can drop this entirely in the future as
+        # the whole ``.run_in_actor()`` API should be built "on top of"
+        # this lower level spawn-request-cancel "daemon actor" API where
+        # a local in-actor task nursery is used with one-to-one task
+        # + `await Portal.run()` calls and the results/errors are
+        # handled directly (inline) and errors by the local nursery.
         except (
-
             Exception,
-            trio.MultiError,
+            BaseExceptionGroup,
             trio.Cancelled
 
         ) as err:
@@ -432,18 +432,20 @@ async def _open_and_supervise_one_cancels_all_nursery(
                     with trio.CancelScope(shield=True):
                         await anursery.cancel()
 
-                # use `MultiError` as needed
+                # use `BaseExceptionGroup` as needed
                 if len(errors) > 1:
-                    raise trio.MultiError(tuple(errors.values()))
+                    raise BaseExceptionGroup(
+                        'tractor.ActorNursery errored with',
+                        tuple(errors.values()),
+                    )
                 else:
                     raise list(errors.values())[0]
 
-        # ria_nursery scope end - nursery checkpoint
-
-    # after nursery exit
+        # da_nursery scope end - nursery checkpoint
+    # final exit
 
 
-@asynccontextmanager
+@acm
 async def open_nursery(
     **kwargs,
 

tractor/experimental/_pubsub.py

@@ -48,7 +48,7 @@ log = get_logger('messaging')
 async def fan_out_to_ctxs(
     pub_async_gen_func: typing.Callable,  # it's an async gen ... gd mypy
     topics2ctxs: dict[str, list],
-    packetizer: typing.Callable = None,
+    packetizer: typing.Callable | None = None,
 ) -> None:
     '''
     Request and fan out quotes to each subscribed actor channel.
@@ -144,7 +144,7 @@ _pubtask2lock: dict[str, trio.StrictFIFOLock] = {}
 
 
 def pub(
-    wrapped: typing.Callable = None,
+    wrapped: typing.Callable | None = None,
     *,
     tasks: set[str] = set(),
 ):
@@ -249,8 +249,8 @@ def pub(
             topics: set[str],
             *args,
             # *,
-            task_name: str = None,  # default: only one task allocated
-            packetizer: Callable = None,
+            task_name: str | None = None,  # default: only one task allocated
+            packetizer: Callable | None = None,
             **kwargs,
         ):
             if task_name is None:

tractor/log.py

@@ -18,12 +18,14 @@
 Log like a forester!
 
 """
+from collections.abc import Mapping
 import sys
 import logging
 import colorlog  # type: ignore
-from typing import Optional
 
-from ._state import ActorContextInfo
+import trio
+
+from ._state import current_actor
 
 
 _proj_name: str = 'tractor'
@@ -36,7 +38,8 @@ LOG_FORMAT = (
     # "{bold_white}{log_color}{asctime}{reset}"
     "{log_color}{asctime}{reset}"
     " {bold_white}{thin_white}({reset}"
-    "{thin_white}{actor}, {process}, {task}){reset}{bold_white}{thin_white})"
+    "{thin_white}{actor_name}[{actor_uid}], "
+    "{process}, {task}){reset}{bold_white}{thin_white})"
     " {reset}{log_color}[{reset}{bold_log_color}{levelname}{reset}{log_color}]"
     " {log_color}{name}"
     " {thin_white}{filename}{log_color}:{reset}{thin_white}{lineno}{log_color}"
@@ -136,9 +139,40 @@ class StackLevelAdapter(logging.LoggerAdapter):
         )
 
 
+_conc_name_getters = {
+    'task': lambda: trio.lowlevel.current_task().name,
+    'actor': lambda: current_actor(),
+    'actor_name': lambda: current_actor().name,
+    'actor_uid': lambda: current_actor().uid[1][:6],
+}
+
+
+class ActorContextInfo(Mapping):
+    "Dyanmic lookup for local actor and task names"
+    _context_keys = (
+        'task',
+        'actor',
+        'actor_name',
+        'actor_uid',
+    )
+
+    def __len__(self):
+        return len(self._context_keys)
+
+    def __iter__(self):
+        return iter(self._context_keys)
+
+    def __getitem__(self, key: str) -> str:
+        try:
+            return _conc_name_getters[key]()
+        except RuntimeError:
+            # no local actor/task context initialized yet
+            return f'no {key} context'
+
+
 def get_logger(
 
-    name: str = None,
+    name: str | None = None,
     _root_name: str = _proj_name,
 
 ) -> StackLevelAdapter:
@@ -173,7 +207,7 @@ def get_logger(
 
 
 def get_console_log(
-    level: str = None,
+    level: str | None = None,
     **kwargs,
 ) -> logging.LoggerAdapter:
     '''Get the package logger and enable a handler which writes to stderr.

tractor/testing/__init__.py

@@ -1,17 +0,0 @@
-# tractor: structured concurrent "actors".
-# Copyright 2018-eternity Tyler Goodlet.
-
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Affero General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Affero General Public License for more details.
-
-# You should have received a copy of the GNU Affero General Public License
-# along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-from ._tractor_test import tractor_test

tractor/testing/_tractor_test.py

@@ -1,104 +0,0 @@
-# tractor: structured concurrent "actors".
-# Copyright 2018-eternity Tyler Goodlet.
-
-# This program is free software: you can redistribute it and/or modify
-# it under the terms of the GNU Affero General Public License as published by
-# the Free Software Foundation, either version 3 of the License, or
-# (at your option) any later version.
-
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU Affero General Public License for more details.
-
-# You should have received a copy of the GNU Affero General Public License
-# along with this program.  If not, see <https://www.gnu.org/licenses/>.
-
-import inspect
-import platform
-from functools import partial, wraps
-
-import trio
-import tractor
-
-
-__all__ = ['tractor_test']
-
-
-def tractor_test(fn):
-    """
-    Use:
-
-    @tractor_test
-    async def test_whatever():
-        await ...
-
-    If fixtures:
-
-        - ``arb_addr`` (a socket addr tuple where arbiter is listening)
-        - ``loglevel`` (logging level passed to tractor internals)
-        - ``start_method`` (subprocess spawning backend)
-
-    are defined in the `pytest` fixture space they will be automatically
-    injected to tests declaring these funcargs.
-    """
-    @wraps(fn)
-    def wrapper(
-        *args,
-        loglevel=None,
-        arb_addr=None,
-        start_method=None,
-        **kwargs
-    ):
-        # __tracebackhide__ = True
-
-        if 'arb_addr' in inspect.signature(fn).parameters:
-            # injects test suite fixture value to test as well
-            # as `run()`
-            kwargs['arb_addr'] = arb_addr
-
-        if 'loglevel' in inspect.signature(fn).parameters:
-            # allows test suites to define a 'loglevel' fixture
-            # that activates the internal logging
-            kwargs['loglevel'] = loglevel
-
-        if start_method is None:
-            if platform.system() == "Windows":
-                start_method = 'spawn'
-            else:
-                start_method = 'trio'
-
-        if 'start_method' in inspect.signature(fn).parameters:
-            # set of subprocess spawning backends
-            kwargs['start_method'] = start_method
-
-        if kwargs:
-
-            # use explicit root actor start
-
-            async def _main():
-                async with tractor.open_root_actor(
-                    # **kwargs,
-                    arbiter_addr=arb_addr,
-                    loglevel=loglevel,
-                    start_method=start_method,
-
-                    # TODO: only enable when pytest is passed --pdb
-                    # debug_mode=True,
-
-                ) as actor:
-                    await fn(*args, **kwargs)
-
-            main = _main
-
-        else:
-            # use implicit root actor start
-            main = partial(fn, *args, **kwargs)
-
-        return trio.run(main)
-            # arbiter_addr=arb_addr,
-            # loglevel=loglevel,
-            # start_method=start_method,
-        # )
-
-    return wrapper

tractor/to_asyncio.py

@@ -466,11 +466,11 @@ async def open_channel_from(
         ):
             # sync to a "started()"-like first delivered value from the
             # ``asyncio`` task.
+            try:
+                with chan._trio_cs:
                     first = await chan.receive()
 
                     # deliver stream handle upward
-            try:
-                with chan._trio_cs:
                     yield first, chan
             finally:
                 chan._trio_exited = True
@@ -491,16 +491,18 @@ def run_as_asyncio_guest(
     SC semantics.
 
     '''
-    # Uh, oh. :o
+    # Uh, oh.
+    #
+    # :o
 
     # It looks like your event loop has caught a case of the ``trio``s.
 
     # :()
 
-    # Don't worry, we've heard you'll barely notice. You might hallucinate
-    # a few more propagating errors and feel like your digestion has
-    # slowed but if anything get's too bad your parents will know about
-    # it.
+    # Don't worry, we've heard you'll barely notice. You might
+    # hallucinate a few more propagating errors and feel like your
+    # digestion has slowed but if anything get's too bad your parents
+    # will know about it.
 
     # :)
 

tractor/trionics/__init__.py

@@ -21,6 +21,7 @@ Sugary patterns for trio + tractor designs.
 from ._mngrs import (
     gather_contexts,
     maybe_open_context,
+    maybe_open_nursery,
 )
 from ._broadcast import (
     broadcast_receiver,
@@ -35,4 +36,5 @@ __all__ = [
     'BroadcastReceiver',
     'Lagged',
     'maybe_open_context',
+    'maybe_open_nursery',
 ]

tractor/trionics/_broadcast.py

@@ -23,7 +23,6 @@ from __future__ import annotations
 from abc import abstractmethod
 from collections import deque
 from contextlib import asynccontextmanager
-from dataclasses import dataclass
 from functools import partial
 from operator import ne
 from typing import Optional, Callable, Awaitable, Any, AsyncIterator, Protocol
@@ -33,7 +32,10 @@ import trio
 from trio._core._run import Task
 from trio.abc import ReceiveChannel
 from trio.lowlevel import current_task
+from msgspec import Struct
+from tractor.log import get_logger
 
+log = get_logger(__name__)
 
 # A regular invariant generic type
 T = TypeVar("T")
@@ -86,8 +88,7 @@ class Lagged(trio.TooSlowError):
     '''
 
 
-@dataclass
-class BroadcastState:
+class BroadcastState(Struct):
     '''
     Common state to all receivers of a broadcast.
 
@@ -110,7 +111,35 @@ class BroadcastState:
     eoc: bool = False
 
     # If the broadcaster was cancelled, we might as well track it
-    cancelled: bool = False
+    cancelled: dict[int, Task] = {}
+
+    def statistics(self) -> dict[str, Any]:
+        '''
+        Return broadcast receiver group "statistics" like many of
+        ``trio``'s internal task-sync primitives.
+
+        '''
+        key: int | None
+        ev: trio.Event | None
+
+        subs = self.subs
+        if self.recv_ready is not None:
+            key, ev = self.recv_ready
+        else:
+            key = ev = None
+
+        qlens: dict[int, int] = {}
+        for tid, sz in subs.items():
+            qlens[tid] = sz if sz != -1 else 0
+
+        return {
+            'open_consumers': len(subs),
+            'queued_len_by_task': qlens,
+            'max_buffer_size': self.maxlen,
+            'tasks_waiting': ev.statistics().tasks_waiting if ev else 0,
+            'tasks_cancelled': self.cancelled,
+            'next_value_receiver_id': key,
+        }
 
 
 class BroadcastReceiver(ReceiveChannel):
@@ -128,23 +157,40 @@ class BroadcastReceiver(ReceiveChannel):
         rx_chan: AsyncReceiver,
         state: BroadcastState,
         receive_afunc: Optional[Callable[[], Awaitable[Any]]] = None,
+        raise_on_lag: bool = True,
 
     ) -> None:
 
         # register the original underlying (clone)
         self.key = id(self)
         self._state = state
+
+        # each consumer has an int count which indicates
+        # which index contains the next value that the task has not yet
+        # consumed and thus should read. In the "up-to-date" case the
+        # consumer task must wait for a new value from the underlying
+        # receiver and we use ``-1`` as the sentinel for this state.
         state.subs[self.key] = -1
 
         # underlying for this receiver
         self._rx = rx_chan
         self._recv = receive_afunc or rx_chan.receive
         self._closed: bool = False
+        self._raise_on_lag = raise_on_lag
 
-    async def receive(self) -> ReceiveType:
+    def receive_nowait(
+        self,
+        _key: int | None = None,
+        _state: BroadcastState | None = None,
 
-        key = self.key
-        state = self._state
+    ) -> Any:
+        '''
+        Sync version of `.receive()` which does all the low level work
+        of receiving from the underlying/wrapped receive channel.
+
+        '''
+        key = _key or self.key
+        state = _state or self._state
 
         # TODO: ideally we can make some way to "lock out" the
         # underlying receive channel in some way such that if some task
@@ -177,32 +223,47 @@ class BroadcastReceiver(ReceiveChannel):
                 # return this value."
                 # https://docs.rs/tokio/1.11.0/tokio/sync/broadcast/index.html#lagging
 
+                mxln = state.maxlen
+                lost = seq - mxln
+
                 # decrement to the last value and expect
                 # consumer to either handle the ``Lagged`` and come back
                 # or bail out on its own (thus un-subscribing)
-                state.subs[key] = state.maxlen - 1
+                state.subs[key] = mxln - 1
 
                 # this task was overrun by the producer side
                 task: Task = current_task()
-                raise Lagged(f'Task {task.name} was overrun')
+                msg = f'Task `{task.name}` overrun and dropped `{lost}` values'
+
+                if self._raise_on_lag:
+                    raise Lagged(msg)
+                else:
+                    log.warning(msg)
+                    return self.receive_nowait(_key, _state)
 
             state.subs[key] -= 1
             return value
 
-        # current task already has the latest value **and** is the
-        # first task to begin waiting for a new one
-        if state.recv_ready is None:
+        raise trio.WouldBlock
+
+    async def _receive_from_underlying(
+        self,
+        key: int,
+        state: BroadcastState,
+
+    ) -> ReceiveType:
 
         if self._closed:
             raise trio.ClosedResourceError
 
         event = trio.Event()
+        assert state.recv_ready is None
         state.recv_ready = key, event
 
+        try:
             # if we're cancelled here it should be
             # fine to bail without affecting any other consumers
             # right?
-            try:
             value = await self._recv()
 
             # items with lower indices are "newer"
@@ -220,7 +281,6 @@ class BroadcastReceiver(ReceiveChannel):
             # already retreived the last value
 
             # XXX: which of these impls is fastest?
-
             # subs = state.subs.copy()
             # subs.pop(key)
 
@@ -251,54 +311,85 @@ class BroadcastReceiver(ReceiveChannel):
             # consumers will be awoken with a sequence of -1
             # and will potentially try to rewait the underlying
             # receiver instead of just cancelling immediately.
-                self._state.cancelled = True
+            self._state.cancelled[key] = current_task()
             if event.statistics().tasks_waiting:
                 event.set()
             raise
 
         finally:
-
             # Reset receiver waiter task event for next blocking condition.
             # this MUST be reset even if the above ``.recv()`` call
             # was cancelled to avoid the next consumer from blocking on
             # an event that won't be set!
             state.recv_ready = None
 
+    async def receive(self) -> ReceiveType:
+        key = self.key
+        state = self._state
+
+        try:
+            return self.receive_nowait(
+                _key=key,
+                _state=state,
+            )
+        except trio.WouldBlock:
+            pass
+
+        # current task already has the latest value **and** is the
+        # first task to begin waiting for a new one so we begin blocking
+        # until rescheduled with the a new value from the underlying.
+        if state.recv_ready is None:
+            return await self._receive_from_underlying(key, state)
+
         # This task is all caught up and ready to receive the latest
-        # value, so queue sched it on the internal event.
+        # value, so queue/schedule it to be woken on the next internal
+        # event.
         else:
-            seq = state.subs[key]
-            assert seq == -1  # sanity
+            while state.recv_ready is not None:
+                # seq = state.subs[key]
+                # assert seq == -1  # sanity
                 _, ev = state.recv_ready
                 await ev.wait()
+                try:
+                    return self.receive_nowait(
+                        _key=key,
+                        _state=state,
+                    )
+                except trio.WouldBlock:
+                    if self._closed:
+                        raise trio.ClosedResourceError
 
-            # NOTE: if we ever would like the behaviour where if the
-            # first task to recv on the underlying is cancelled but it
-            # still DOES trigger the ``.recv_ready``, event we'll likely need
-            # this logic:
+                    subs = state.subs
+                    if (
+                        len(subs) == 1
+                        and key in subs
+                        # or cancelled
+                    ):
+                        # XXX: we are the last and only user of this BR so
+                        # likely it makes sense to unwind back to the
+                        # underlying?
+                        # import tractor
+                        # await tractor.breakpoint()
+                        log.warning(
+                            f'Only one sub left for {self}?\n'
+                            'We can probably unwind from breceiver?'
+                        )
 
-            if seq > -1:
-                # stuff from above..
-                seq = state.subs[key]
-
-                value = state.queue[seq]
-                state.subs[key] -= 1
-                return value
-
-            elif seq == -1:
                     # XXX: In the case where the first task to allocate the
-                # ``.recv_ready`` event is cancelled we will be woken with
-                # a non-incremented sequence number and thus will read the
-                # oldest value if we use that. Instead we need to detect if
-                # we have not been incremented and then receive again.
-                return await self.receive()
+                    # ``.recv_ready`` event is cancelled we will be woken
+                    # with a non-incremented sequence number (the ``-1``
+                    # sentinel) and thus will read the oldest value if we
+                    # use that. Instead we need to detect if we have not
+                    # been incremented and then receive again.
+                    # return await self.receive()
 
-            else:
-                raise ValueError(f'Invalid sequence {seq}!?')
+            return await self._receive_from_underlying(key, state)
 
     @asynccontextmanager
     async def subscribe(
         self,
+        raise_on_lag: bool = True,
+
     ) -> AsyncIterator[BroadcastReceiver]:
         '''
         Subscribe for values from this broadcast receiver.
@@ -316,6 +407,7 @@ class BroadcastReceiver(ReceiveChannel):
             rx_chan=self._rx,
             state=state,
             receive_afunc=self._recv,
+            raise_on_lag=raise_on_lag,
         )
         # assert clone in state.subs
         assert br.key in state.subs
@@ -352,7 +444,8 @@ def broadcast_receiver(
 
     recv_chan: AsyncReceiver,
     max_buffer_size: int,
-    **kwargs,
+    receive_afunc: Optional[Callable[[], Awaitable[Any]]] = None,
+    raise_on_lag: bool = True,
 
 ) -> BroadcastReceiver:
 
@@ -363,5 +456,6 @@ def broadcast_receiver(
             maxlen=max_buffer_size,
             subs={},
         ),
-        **kwargs,
+        receive_afunc=receive_afunc,
+        raise_on_lag=raise_on_lag,
     )

tractor/trionics/_mngrs.py

@@ -19,6 +19,7 @@ Async context manager primitives with hard ``trio``-aware semantics
 
 '''
 from contextlib import asynccontextmanager as acm
+import inspect
 from typing import (
     Any,
     AsyncContextManager,
@@ -34,8 +35,8 @@ from typing import (
 import trio
 from trio_typing import TaskStatus
 
-from ..log import get_logger
 from .._state import current_actor
+from ..log import get_logger
 
 
 log = get_logger(__name__)
@@ -44,6 +45,25 @@ log = get_logger(__name__)
 T = TypeVar("T")
 
 
+@acm
+async def maybe_open_nursery(
+    nursery: trio.Nursery | None = None,
+    shield: bool = False,
+) -> AsyncGenerator[trio.Nursery, Any]:
+    '''
+    Create a new nursery if None provided.
+
+    Blocks on exit as expected if no input nursery is provided.
+
+    '''
+    if nursery is not None:
+        yield nursery
+    else:
+        async with trio.open_nursery() as nursery:
+            nursery.cancel_scope.shield = shield
+            yield nursery
+
+
 async def _enter_and_wait(
 
     mngr: AsyncContextManager[T],
@@ -89,6 +109,17 @@ async def gather_contexts(
     all_entered = trio.Event()
     parent_exit = trio.Event()
 
+    # XXX: ensure greedy sequence of manager instances
+    # since a lazy inline generator doesn't seem to work
+    # with `async with` syntax.
+    mngrs = list(mngrs)
+
+    if not mngrs:
+        raise ValueError(
+            'input mngrs is empty?\n'
+            'Did try to use inline generator syntax?'
+        )
+
     async with trio.open_nursery() as n:
         for mngr in mngrs:
             n.start_soon(
@@ -102,12 +133,12 @@ async def gather_contexts(
         # deliver control once all managers have started up
         await all_entered.wait()
 
-        # NOTE: order *should* be preserved in the output values
-        # since ``dict``s are now implicitly ordered.
+        try:
             yield tuple(unwrapped.values())
-
-        # we don't need a try/finally since cancellation will be triggered
-        # by the surrounding nursery on error.
+        finally:
+            # NOTE: this is ABSOLUTELY REQUIRED to avoid
+            # the following wacky bug:
+            # <tractorbugurlhere>
             parent_exit.set()
 
 
@@ -121,6 +152,7 @@ class _Cache:
     a kept-alive-while-in-use async resource.
 
     '''
+    service_n: Optional[trio.Nursery] = None
     locks: dict[Hashable, trio.Lock] = {}
     users: int = 0
     values: dict[Any,  Any] = {}
@@ -128,6 +160,7 @@ class _Cache:
         Hashable,
         tuple[trio.Nursery, trio.Event]
     ] = {}
+    # nurseries: dict[int, trio.Nursery] = {}
     no_more_users: Optional[trio.Event] = None
 
     @classmethod
@@ -158,7 +191,7 @@ async def maybe_open_context(
     # XXX: used as cache key after conversion to tuple
     # and all embedded values must also be hashable
     kwargs: dict = {},
-    key: Hashable = None,
+    key: Hashable | Callable[..., Hashable] = None,
 
 ) -> AsyncIterator[tuple[bool, T]]:
     '''
@@ -168,8 +201,14 @@ async def maybe_open_context(
 
     '''
     fid = id(acm_func)
+
+    if inspect.isfunction(key):
+        ctx_key = (fid, key(**kwargs))
+    else:
         ctx_key = (fid, key or tuple(kwargs.items()))
-    value = None
+
+    # yielded output
+    yielded: Any = None
 
     # Lock resource acquisition around task racing  / ``trio``'s
     # scheduler protocol.
@@ -179,44 +218,51 @@ async def maybe_open_context(
     lock = _Cache.locks.setdefault(fid, trio.Lock())
     await lock.acquire()
 
+    # XXX: one singleton nursery per actor and we want to
+    # have it not be closed until all consumers have exited (which is
+    # currently difficult to implement any other way besides using our
+    # pre-allocated runtime instance..)
+    service_n: trio.Nursery = current_actor()._service_n
+
+    # TODO: is there any way to allocate
+    # a 'stays-open-till-last-task-finshed nursery?
+    # service_n: trio.Nursery
+    # async with maybe_open_nursery(_Cache.service_n) as service_n:
+    #     _Cache.service_n = service_n
+
     try:
         # **critical section** that should prevent other tasks from
         # checking the _Cache until complete otherwise the scheduler
         # may switch and by accident we create more then one resource.
-        value = _Cache.values[ctx_key]
+        yielded = _Cache.values[ctx_key]
 
     except KeyError:
         log.info(f'Allocating new {acm_func} for {ctx_key}')
-
         mngr = acm_func(**kwargs)
-        # TODO: avoid pulling from ``tractor`` internals and
-        # instead offer a "root nursery" in piker actors?
-        service_n = current_actor()._service_n
-
-        # TODO: does this need to be a tractor "root nursery"?
         resources = _Cache.resources
         assert not resources.get(ctx_key), f'Resource exists? {ctx_key}'
         resources[ctx_key] = (service_n, trio.Event())
 
-        value = await service_n.start(
+        # sync up to the mngr's yielded value
+        yielded = await service_n.start(
             _Cache.run_ctx,
             mngr,
             ctx_key,
         )
         _Cache.users += 1
         lock.release()
-        yield False, value
+        yield False, yielded
 
     else:
         log.info(f'Reusing _Cached resource for {ctx_key}')
         _Cache.users += 1
         lock.release()
-        yield True, value
+        yield True, yielded
 
     finally:
         _Cache.users -= 1
 
-        if value is not None:
+        if yielded is not None:
             # if no more consumers, teardown the client
             if _Cache.users <= 0:
                 log.info(f'De-allocating resource for {ctx_key}')