Merge pull request #358 from goodboy/switch_to_pdbp

Switch to `pdbp` 🏄🏼

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
@@ -118,7 +125,7 @@ Zombie safe: self-destruct a process tree
             f"running in pid {os.getpid()}"
         )
 
-       await trio.sleep_forever()
+        await trio.sleep_forever()
 
 
     async def main():
@@ -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/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/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/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.

requirements-test.txt

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

setup.py

@@ -26,12 +26,12 @@ 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=[
@@ -52,16 +52,14 @@ setup(
         # tooling
         'tricycle',
         'trio_typing',
-
-        # tooling
         'colorlog',
         'wrapt',
 
-        # serialization
+        # IPC serialization
         'msgspec',
 
         # debug mode REPL
-        'pdbpp',
+        'pdbp',
 
         # pip ref docs on these specs:
         # https://pip.pypa.io/en/stable/reference/requirement-specifiers/#examples
@@ -73,10 +71,9 @@ setup(
         # https://github.com/pdbpp/fancycompleter/issues/37
         'pyreadline3 ; platform_system == "Windows"',
 
-
     ],
     tests_require=['pytest'],
-    python_requires=">=3.9",
+    python_requires=">=3.10",
     keywords=[
         'trio',
         'async',

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_debugger.py

@@ -95,7 +95,7 @@ def spawn(
     return _spawn
 
 
-PROMPT = r"\(Pdb\+\+\)"
+PROMPT = r"\(Pdb\+\)"
 
 
 def expect(
@@ -151,18 +151,6 @@ 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..')
-
     node = request.node
     markers = node.own_markers
     for mark in markers:
@@ -193,13 +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())
@@ -230,8 +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)
 
@@ -272,7 +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:
@@ -291,7 +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)
@@ -301,7 +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..
@@ -312,10 +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')
@@ -338,8 +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
@@ -359,7 +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
@@ -386,8 +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
@@ -396,7 +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)
@@ -404,7 +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
 
@@ -415,7 +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
@@ -447,8 +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
@@ -460,7 +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)
@@ -469,7 +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
@@ -481,7 +471,7 @@ def test_multi_subactors(
     child.sendline('c')
 
     # 2nd name_error failure
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     # TODO: will we ever get the race where this crash will show up?
     # blocklist strat now prevents this crash
@@ -495,7 +485,7 @@ def test_multi_subactors(
 
     # 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, [
@@ -578,7 +568,7 @@ def test_multi_daemon_subactors(
     '''
     child = spawn('multi_daemon_subactors')
 
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     # there can be a race for which subactor will acquire
     # the root's tty lock first so anticipate either crash
@@ -608,7 +598,7 @@ def test_multi_daemon_subactors(
     # second entry by `bp_forever`.
 
     child.sendline('c')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
     assert_before(child, [next_msg])
 
     # XXX: hooray the root clobbering the child here was fixed!
@@ -630,7 +620,7 @@ def test_multi_daemon_subactors(
 
     # expect another breakpoint actor entry
     child.sendline('c')
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     try:
         assert_before(child, [bp_forever_msg])
@@ -646,7 +636,7 @@ def test_multi_daemon_subactors(
         # after 1 or more further bp actor entries.
 
         child.sendline('c')
-        child.expect(r"\(Pdb\+\+\)")
+        child.expect(PROMPT)
         assert_before(child, [name_error_msg])
 
     # wait for final error in root
@@ -654,7 +644,7 @@ def test_multi_daemon_subactors(
     while True:
         try:
             child.sendline('c')
-            child.expect(r"\(Pdb\+\+\)")
+            child.expect(PROMPT)
             assert_before(
                 child,
                 [bp_forever_msg]
@@ -687,8 +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())
@@ -703,7 +693,7 @@ def test_multi_subactors_root_errors(
 
     # due to block list strat from #337, this will no longer
     # propagate before the root errors and cancels the spawner sub-tree.
-    child.expect(r"\(Pdb\+\+\)")
+    child.expect(PROMPT)
 
     # only if the blocking condition doesn't kick in fast enough
     before = str(child.before.decode())
@@ -718,7 +708,7 @@ 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
@@ -735,7 +725,7 @@ 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, [
@@ -784,7 +774,7 @@ def test_multi_nested_subactors_error_through_nurseries(
 
     for send_char in itertools.cycle(['c', 'q']):
         try:
-            child.expect(r"\(Pdb\+\+\)")
+            child.expect(PROMPT)
             child.sendline(send_char)
             time.sleep(0.01)
 
@@ -826,7 +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
@@ -841,7 +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,
@@ -898,7 +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
@@ -915,7 +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_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

@@ -24,7 +24,6 @@ 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,
@@ -64,7 +66,6 @@ __all__ = [
     'MsgStream',
     'BaseExceptionGroup',
     'Portal',
-    'ReceiveMsgStream',
     'RemoteActorError',
     'breakpoint',
     'context',

tractor/_debug.py

@@ -37,6 +37,7 @@ from typing import (
 )
 from types import FrameType
 
+import pdbp
 import tractor
 import trio
 from trio_typing import TaskStatus
@@ -53,17 +54,6 @@ from ._exceptions import (
 )
 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__)
 
 
@@ -154,22 +144,26 @@ class Lock:
             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):
@@ -313,7 +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.
 
@@ -433,7 +427,7 @@ async def wait_for_parent_stdin_hijack(
 def mk_mpdb() -> tuple[MultiActorPdb, Callable]:
 
     pdb = MultiActorPdb()
-    # signal.signal = pdbpp.hideframe(signal.signal)
+    # signal.signal = pdbp.hideframe(signal.signal)
 
     Lock.shield_sigint()
 
@@ -583,7 +577,7 @@ 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 = pdbp.hideframe(signal.signal)
 
 
 def shield_sigint_handler(
@@ -743,13 +737,13 @@ def shield_sigint_handler(
         # 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
 
 
 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()
@@ -759,7 +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?
@@ -768,7 +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)
@@ -798,7 +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(

tractor/_portal.py

@@ -45,7 +45,10 @@ from ._exceptions import (
     NoResult,
     ContextCancelled,
 )
-from ._streaming import Context, ReceiveMsgStream
+from ._streaming import (
+    Context,
+    MsgStream,
+)
 
 
 log = get_logger(__name__)
@@ -101,7 +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(
@@ -316,7 +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 (
@@ -341,7 +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)

tractor/_root.py

@@ -22,8 +22,9 @@ from contextlib import asynccontextmanager
 from functools import partial
 import importlib
 import logging
-import os
 import signal
+import sys
+import os
 import typing
 import warnings
 
@@ -84,8 +85,10 @@ async def open_root_actor(
 
     '''
     # 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
@@ -254,6 +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")
 
 
@@ -289,7 +301,7 @@ def run_daemon(
     async def _main():
 
         async with open_root_actor(
-            arbiter_addr=registry_addr,
+            registry_addr=registry_addr,
             name=name,
             start_method=start_method,
             debug_mode=debug_mode,

tractor/_spawn.py

@@ -23,13 +23,12 @@ import sys
 import platform
 from typing import (
     Any,
+    Awaitable,
     Literal,
-    Optional,
     Callable,
     TypeVar,
     TYPE_CHECKING,
 )
-from collections.abc import Awaitable
 
 from exceptiongroup import BaseExceptionGroup
 import trio
@@ -60,7 +59,7 @@ if TYPE_CHECKING:
 log = get_logger('tractor')
 
 # placeholder for an mp start context if so using that backend
-_ctx: Optional[mp.context.BaseContext] = None
+_ctx: mp.context.BaseContext | None = None
 SpawnMethodKey = Literal[
     'trio',  # supported on all platforms
     'mp_spawn',
@@ -86,7 +85,7 @@ else:
 def try_set_start_method(
     key: SpawnMethodKey
 
-) -> Optional[mp.context.BaseContext]:
+) -> mp.context.BaseContext | None:
     '''
     Attempt to set the method for process starting, aka the "actor
     spawning backend".
@@ -200,16 +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
@@ -355,12 +375,11 @@ async def trio_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(    # type: ignore
-                spawn_cmd)
+            proc = await trio.lowlevel.open_process(spawn_cmd)
 
             log.runtime(f"Started {proc}")
 
@@ -444,8 +463,8 @@ async def trio_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 {subactor.uid}')

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:
 
@@ -317,15 +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

tractor/_supervise.py

@@ -302,7 +302,7 @@ async def _open_and_supervise_one_cancels_all_nursery(
 ) -> typing.AsyncGenerator[ActorNursery, None]:
 
     # TODO: yay or nay?
-    # __tracebackhide__ = True
+    __tracebackhide__ = True
 
     # the collection of errors retreived from spawned sub-actors
     errors: dict[tuple[str, str], BaseException] = {}

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
@@ -177,128 +223,173 @@ 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
 
-            if self._closed:
-                raise trio.ClosedResourceError
+    async def _receive_from_underlying(
+        self,
+        key: int,
+        state: BroadcastState,
 
-            event = trio.Event()
-            state.recv_ready = key, event
+    ) -> 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()
+            value = await self._recv()
 
-                # items with lower indices are "newer"
-                # NOTE: ``collections.deque`` implicitly takes care of
-                # trucating values outside our ``state.maxlen``. In the
-                # alt-backend-array-case we'll need to make sure this is
-                # implemented in similar ringer-buffer-ish style.
-                state.queue.appendleft(value)
+            # items with lower indices are "newer"
+            # NOTE: ``collections.deque`` implicitly takes care of
+            # trucating values outside our ``state.maxlen``. In the
+            # alt-backend-array-case we'll need to make sure this is
+            # implemented in similar ringer-buffer-ish style.
+            state.queue.appendleft(value)
 
-                # broadcast new value to all subscribers by increasing
-                # all sequence numbers that will point in the queue to
-                # their latest available value.
+            # broadcast new value to all subscribers by increasing
+            # all sequence numbers that will point in the queue to
+            # their latest available value.
 
-                # don't decrement the sequence for this task since we
-                # already retreived the last value
+            # don't decrement the sequence for this task since we
+            # already retreived the last value
 
-                # XXX: which of these impls is fastest?
+            # XXX: which of these impls is fastest?
+            # subs = state.subs.copy()
+            # subs.pop(key)
 
-                # subs = state.subs.copy()
-                # subs.pop(key)
-
-                for sub_key in filter(
-                    # lambda k: k != key, state.subs,
-                    partial(ne, key), state.subs,
-                ):
-                    state.subs[sub_key] += 1
-
-                # NOTE: this should ONLY be set if the above task was *NOT*
-                # cancelled on the `._recv()` call.
-                event.set()
-                return value
-
-            except trio.EndOfChannel:
-                # if any one consumer gets an EOC from the underlying
-                # receiver we need to unblock and send that signal to
-                # all other consumers.
-                self._state.eoc = True
-                if event.statistics().tasks_waiting:
-                    event.set()
-                raise
-
-            except (
-                trio.Cancelled,
+            for sub_key in filter(
+                # lambda k: k != key, state.subs,
+                partial(ne, key), state.subs,
             ):
-                # handle cancelled specially otherwise sibling
-                # 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
-                if event.statistics().tasks_waiting:
-                    event.set()
-                raise
+                state.subs[sub_key] += 1
 
-            finally:
+            # NOTE: this should ONLY be set if the above task was *NOT*
+            # cancelled on the `._recv()` call.
+            event.set()
+            return value
 
-                # 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
+        except trio.EndOfChannel:
+            # if any one consumer gets an EOC from the underlying
+            # receiver we need to unblock and send that signal to
+            # all other consumers.
+            self._state.eoc = True
+            if event.statistics().tasks_waiting:
+                event.set()
+            raise
+
+        except (
+            trio.Cancelled,
+        ):
+            # handle cancelled specially otherwise sibling
+            # 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[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
-            _, ev = state.recv_ready
-            await ev.wait()
+            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]
+                    # 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 (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()
 
-                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()
-
-            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,
     )