Change `tractor.breakpoint()` to new `.pause()` in test suite

Ensuring we can at least use `breakpoint()` from an infected actor's
`asyncio.Task` spawned via a `.to_asyncio` API.

Also includes a little `tests/devx/` reorging,
- start splitting out non-`tractor.pause()` tests into a new
  `test_pause_from_non_trio.py` for all the `.pause_from_sync()`
  use in bg-threaded or `asyncio` applications.
- factor harness commonalities to the `devx/conftest` (namely
  the `do_ctlc()` masher).
- mv `test_pause_from_sync` to the new non`-trio` mod.

NOTE, the `ctlc=True` is still failing for
`test_pause_from_asyncio_task` which is a user-happiness bug but not
anything fundamentally broken - just need to handle the `asyncio` case
in `.devx._debug.sigint_shield()`!

examples/debugging/asyncio_bp.py

@@ -1,3 +1,8 @@
+'''
+Examples of using the builtin `breakpoint()` from an `asyncio.Task`
+running in a subactor spawned with `infect_asyncio=True`.
+
+'''
 import asyncio
 
 import trio
@@ -26,15 +31,16 @@ async def bp_then_error(
     # NOTE: what happens here inside the hook needs some refinement..
     # => seems like it's still `._debug._set_trace()` but
     #    we set `Lock.local_task_in_debug = 'sync'`, we probably want
-    #    some further, at least, meta-data about the task/actoq in debug
+    #    some further, at least, meta-data about the task/actor in debug
-    #    in terms of making it clear it's asyncio mucking about.
+    #    in terms of making it clear it's `asyncio` mucking about.
     breakpoint()
 
+
     # short checkpoint / delay
-    await asyncio.sleep(0.5)
+    await asyncio.sleep(0.5)  # asyncio-side
 
     if raise_after_bp:
-        raise ValueError('blah')
+        raise ValueError('asyncio side error!')
 
     # TODO: test case with this so that it gets cancelled?
     else:
@@ -46,7 +52,7 @@ async def bp_then_error(
 @tractor.context
 async def trio_ctx(
     ctx: tractor.Context,
-    bp_before_started: bool = True,
+    bp_before_started: bool = False,
 ):
 
     # this will block until the ``asyncio`` task sends a "first"
@@ -55,19 +61,19 @@ async def trio_ctx(
 
         to_asyncio.open_channel_from(
             bp_then_error,
-            raise_after_bp=not bp_before_started,
+            # raise_after_bp=not bp_before_started,
         ) as (first, chan),
 
-        trio.open_nursery() as n,
+        trio.open_nursery() as tn,
     ):
         assert first == 'start'
 
         if bp_before_started:
-            await tractor.breakpoint()
+            await tractor.pause()
 
-        await ctx.started(first)
+        await ctx.started(first)  # trio-side
 
-        n.start_soon(
+        tn.start_soon(
             to_asyncio.run_task,
             aio_sleep_forever,
         )
@@ -77,14 +83,18 @@ async def trio_ctx(
 async def main(
     bps_all_over: bool = True,
 
+    # TODO, WHICH OF THESE HAZ BUGZ?
+    cancel_from_root: bool = False,
+    err_from_root: bool = False,
+
 ) -> None:
 
     async with tractor.open_nursery(
         debug_mode=True,
         maybe_enable_greenback=True,
         # loglevel='devx',
-    ) as n:
+    ) as an:
-        ptl: Portal = await n.start_actor(
+        ptl: Portal = await an.start_actor(
             'aio_daemon',
             enable_modules=[__name__],
             infect_asyncio=True,
@@ -99,12 +109,18 @@ async def main(
 
             assert first == 'start'
 
-            if bps_all_over:
+            # pause in parent to ensure no cross-actor
-                await tractor.breakpoint()
+            # locking problems exist!
+            await tractor.pause()
+
+            if cancel_from_root:
+                await ctx.cancel()
+
+            if err_from_root:
+                assert 0
+            else:
+                await trio.sleep_forever()
 
-            # await trio.sleep_forever()
-            await ctx.cancel()
-            assert 0
 
         # TODO: case where we cancel from trio-side while asyncio task
         # has debugger lock?

examples/debugging/fast_error_in_root_after_spawn.py

@@ -1,5 +1,5 @@
 '''
-Fast fail test with a context.
+Fast fail test with a `Context`.
 
 Ensure the partially initialized sub-actor process
 doesn't cause a hang on error/cancel of the parent

examples/debugging/multi_daemon_subactors.py

@@ -7,7 +7,7 @@ async def breakpoint_forever():
     try:
         while True:
             yield 'yo'
-            await tractor.breakpoint()
+            await tractor.pause()
     except BaseException:
         tractor.log.get_console_log().exception(
             'Cancelled while trying to enter pause point!'

examples/debugging/multi_nested_subactors_error_up_through_nurseries.py

@@ -10,7 +10,7 @@ async def name_error():
 async def breakpoint_forever():
     "Indefinitely re-enter debugger in child actor."
     while True:
-        await tractor.breakpoint()
+        await tractor.pause()
 
         # NOTE: if the test never sent 'q'/'quit' commands
         # on the pdb repl, without this checkpoint line the

examples/debugging/multi_subactors.py

@@ -6,7 +6,7 @@ async def breakpoint_forever():
     "Indefinitely re-enter debugger in child actor."
     while True:
         await trio.sleep(0.1)
-        await tractor.breakpoint()
+        await tractor.pause()
 
 
 async def name_error():

examples/debugging/restore_builtin_breakpoint.py

@@ -6,19 +6,46 @@ import tractor
 
 
 async def main() -> None:
-    async with tractor.open_nursery(debug_mode=True) as an:
 
-        assert os.environ['PYTHONBREAKPOINT'] == 'tractor._debug._set_trace'
+    # intially unset, no entry.
+    orig_pybp_var: int = os.environ.get('PYTHONBREAKPOINT')
+    assert orig_pybp_var in {None, "0"}
+
+    async with tractor.open_nursery(
+        debug_mode=True,
+    ) as an:
+        assert an
+        assert (
+            (pybp_var := os.environ['PYTHONBREAKPOINT'])
+            ==
+            'tractor.devx._debug._sync_pause_from_builtin'
+        )
 
         # TODO: an assert that verifies the hook has indeed been, hooked
         # XD
-        assert sys.breakpointhook is not tractor._debug._set_trace
+        assert (
+            (pybp_hook := sys.breakpointhook)
+            is not tractor.devx._debug._set_trace
+        )
 
+        print(
+            f'$PYTHONOBREAKPOINT: {pybp_var!r}\n'
+            f'`sys.breakpointhook`: {pybp_hook!r}\n'
+        )
         breakpoint()
+        pass  # first bp, tractor hook set.
 
-    # TODO: an assert that verifies the hook is unhooked..
+    # XXX AFTER EXIT (of actor-runtime) verify the hook is unset..
+    #
+    # YES, this is weird but it's how stdlib docs say to do it..
+    # https://docs.python.org/3/library/sys.html#sys.breakpointhook
+    assert os.environ.get('PYTHONBREAKPOINT') is orig_pybp_var
     assert sys.breakpointhook
+
+    # now ensure a regular builtin pause still works
     breakpoint()
+    pass  # last bp, stdlib hook restored
+
 
 if __name__ == '__main__':
     trio.run(main)

examples/debugging/root_actor_breakpoint.py

@@ -10,7 +10,7 @@ async def main():
 
         await trio.sleep(0.1)
 
-        await tractor.breakpoint()
+        await tractor.pause()
 
         await trio.sleep(0.1)
 

examples/debugging/root_actor_breakpoint_forever.py

@@ -11,7 +11,7 @@ async def main(
         # loglevel='runtime',
     ):
         while True:
-            await tractor.breakpoint()
+            await tractor.pause()
 
 
 if __name__ == '__main__':

examples/debugging/subactor_bp_in_ctx.py

@@ -4,9 +4,9 @@ import trio
 
 async def gen():
     yield 'yo'
-    await tractor.breakpoint()
+    await tractor.pause()
     yield 'yo'
-    await tractor.breakpoint()
+    await tractor.pause()
 
 
 @tractor.context
@@ -15,7 +15,7 @@ async def just_bp(
 ) -> None:
 
     await ctx.started()
-    await tractor.breakpoint()
+    await tractor.pause()
 
     # TODO: bps and errors in this call..
     async for val in gen():

tests/devx/conftest.py

@@ -2,6 +2,7 @@
 `tractor.devx.*` tooling sub-pkg test space.
 
 '''
+import time
 from typing import (
     Callable,
 )
@@ -11,9 +12,19 @@ from pexpect.exceptions import (
     TIMEOUT,
 )
 from pexpect.spawnbase import SpawnBase
+
 from tractor._testing import (
     mk_cmd,
 )
+from tractor.devx._debug import (
+    _pause_msg as _pause_msg,
+    _crash_msg as _crash_msg,
+    _repl_fail_msg as _repl_fail_msg,
+    _ctlc_ignore_header as _ctlc_ignore_header,
+)
+from conftest import (
+    _ci_env,
+)
 
 
 @pytest.fixture
@@ -107,6 +118,9 @@ def expect(
         raise
 
 
+PROMPT = r"\(Pdb\+\)"
+
+
 def in_prompt_msg(
     child: SpawnBase,
     parts: list[str],
@@ -166,3 +180,40 @@ def assert_before(
         err_on_false=True,
         **kwargs
     )
+
+
+def do_ctlc(
+    child,
+    count: int = 3,
+    delay: float = 0.1,
+    patt: str|None = None,
+
+    # expect repl UX to reprint the prompt after every
+    # ctrl-c send.
+    # XXX: no idea but, in CI this never seems to work even on 3.10 so
+    # needs some further investigation potentially...
+    expect_prompt: bool = not _ci_env,
+
+) -> str|None:
+
+    before: str|None = None
+
+    # make sure ctl-c sends don't do anything but repeat output
+    for _ in range(count):
+        time.sleep(delay)
+        child.sendcontrol('c')
+
+        # TODO: figure out why this makes CI fail..
+        # if you run this test manually it works just fine..
+        if expect_prompt:
+            time.sleep(delay)
+            child.expect(PROMPT)
+            before = str(child.before.decode())
+            time.sleep(delay)
+
+            if patt:
+                # should see the last line on console
+                assert patt in before
+
+    # return the console content up to the final prompt
+    return before

tests/devx/test_debugger.py

@@ -21,14 +21,13 @@ from pexpect.exceptions import (
     EOF,
 )
 
-from tractor.devx._debug import (
+from .conftest import (
+    do_ctlc,
+    PROMPT,
     _pause_msg,
     _crash_msg,
     _repl_fail_msg,
 )
-from conftest import (
-    _ci_env,
-)
 from .conftest import (
     expect,
     in_prompt_msg,
@@ -70,9 +69,6 @@ has_nested_actors = pytest.mark.has_nested_actors
 # )
 
 
-PROMPT = r"\(Pdb\+\)"
-
-
 @pytest.mark.parametrize(
     'user_in_out',
     [
@@ -123,8 +119,10 @@ def test_root_actor_error(
     ids=lambda item: f'{item[0]} -> {item[1]}',
 )
 def test_root_actor_bp(spawn, user_in_out):
-    """Demonstrate breakpoint from in root actor.
+    '''
-    """
+    Demonstrate breakpoint from in root actor.
+
+    '''
     user_input, expect_err_str = user_in_out
     child = spawn('root_actor_breakpoint')
 
@@ -146,43 +144,6 @@ def test_root_actor_bp(spawn, user_in_out):
         assert expect_err_str in str(child.before)
 
 
-def do_ctlc(
-    child,
-    count: int = 3,
-    delay: float = 0.1,
-    patt: str|None = None,
-
-    # expect repl UX to reprint the prompt after every
-    # ctrl-c send.
-    # XXX: no idea but, in CI this never seems to work even on 3.10 so
-    # needs some further investigation potentially...
-    expect_prompt: bool = not _ci_env,
-
-) -> str|None:
-
-    before: str|None = None
-
-    # make sure ctl-c sends don't do anything but repeat output
-    for _ in range(count):
-        time.sleep(delay)
-        child.sendcontrol('c')
-
-        # TODO: figure out why this makes CI fail..
-        # if you run this test manually it works just fine..
-        if expect_prompt:
-            time.sleep(delay)
-            child.expect(PROMPT)
-            before = str(child.before.decode())
-            time.sleep(delay)
-
-            if patt:
-                # should see the last line on console
-                assert patt in before
-
-    # return the console content up to the final prompt
-    return before
-
-
 def test_root_actor_bp_forever(
     spawn,
     ctlc: bool,
@@ -919,138 +880,6 @@ def test_different_debug_mode_per_actor(
     )
 
 
-def test_pause_from_sync(
-    spawn,
-    ctlc: bool
-):
-    '''
-    Verify we can use the `pdbp` REPL from sync functions AND from
-    any thread spawned with `trio.to_thread.run_sync()`.
-
-    `examples/debugging/sync_bp.py`
-
-    '''
-    child = spawn('sync_bp')
-
-    # first `sync_pause()` after nurseries open
-    child.expect(PROMPT)
-    assert_before(
-        child,
-        [
-            # pre-prompt line
-            _pause_msg,
-            "<Task '__main__.main'",
-            "('root'",
-        ]
-    )
-    if ctlc:
-        do_ctlc(child)
-        # ^NOTE^ subactor not spawned yet; don't need extra delay.
-
-    child.sendline('c')
-
-    # first `await tractor.pause()` inside `p.open_context()` body
-    child.expect(PROMPT)
-
-    # XXX shouldn't see gb loaded message with PDB loglevel!
-    assert not in_prompt_msg(
-        child,
-        ['`greenback` portal opened!'],
-    )
-    # should be same root task
-    assert_before(
-        child,
-        [
-            _pause_msg,
-            "<Task '__main__.main'",
-            "('root'",
-        ]
-    )
-
-    if ctlc:
-        do_ctlc(
-            child,
-            # NOTE: setting this to 0 (or some other sufficient
-            # small val) can cause the test to fail since the
-            # `subactor` suffers a race where the root/parent
-            # sends an actor-cancel prior to it hitting its pause
-            # point; by def the value is 0.1
-            delay=0.4,
-        )
-
-    # XXX, fwiw without a brief sleep here the SIGINT might actually
-    # trigger "subactor" cancellation by its parent  before the
-    # shield-handler is engaged.
-    #
-    # => similar to the `delay` input to `do_ctlc()` below, setting
-    # this too low can cause the test to fail since the `subactor`
-    # suffers a race where the root/parent sends an actor-cancel
-    # prior to the context task hitting its pause point (and thus
-    # engaging the `sigint_shield()` handler in time); this value
-    # seems be good enuf?
-    time.sleep(0.6)
-
-    # one of the bg thread or subactor should have
-    # `Lock.acquire()`-ed
-    # (NOT both, which will result in REPL clobbering!)
-    attach_patts: dict[str, list[str]] = {
-        'subactor': [
-            "'start_n_sync_pause'",
-            "('subactor'",
-        ],
-        'inline_root_bg_thread': [
-            "<Thread(inline_root_bg_thread",
-            "('root'",
-        ],
-        'start_soon_root_bg_thread': [
-            "<Thread(start_soon_root_bg_thread",
-            "('root'",
-        ],
-    }
-    conts: int = 0  # for debugging below matching logic on failure
-    while attach_patts:
-        child.sendline('c')
-        conts += 1
-        child.expect(PROMPT)
-        before = str(child.before.decode())
-        for key in attach_patts:
-            if key in before:
-                attach_key: str = key
-                expected_patts: str = attach_patts.pop(key)
-                assert_before(
-                    child,
-                    [_pause_msg]
-                    +
-                    expected_patts
-                )
-                break
-        else:
-            pytest.fail(
-                f'No keys found?\n\n'
-                f'{attach_patts.keys()}\n\n'
-                f'{before}\n'
-            )
-
-        # ensure no other task/threads engaged a REPL
-        # at the same time as the one that was detected above.
-        for key, other_patts in attach_patts.copy().items():
-            assert not in_prompt_msg(
-                child,
-                other_patts,
-            )
-
-        if ctlc:
-            do_ctlc(
-                child,
-                patt=attach_key,
-                # NOTE same as comment above
-                delay=0.4,
-            )
-
-    child.sendline('c')
-    child.expect(EOF)
-
-
 def test_post_mortem_api(
     spawn,
     ctlc: bool,

tests/devx/test_pause_from_non_trio.py

@@ -0,0 +1,329 @@
+'''
+That "foreign loop/thread" debug REPL support better ALSO WORK!
+
+Same as `test_native_pause.py`.
+All these tests can be understood (somewhat) by running the
+equivalent `examples/debugging/` scripts manually.
+
+'''
+# from functools import partial
+# import itertools
+import time
+# from typing import (
+#     Iterator,
+# )
+
+import pytest
+from pexpect.exceptions import (
+    # TIMEOUT,
+    EOF,
+)
+
+from .conftest import (
+    # _ci_env,
+    do_ctlc,
+    PROMPT,
+    # expect,
+    in_prompt_msg,
+    assert_before,
+    _pause_msg,
+    _crash_msg,
+    _ctlc_ignore_header,
+    # _repl_fail_msg,
+)
+
+
+def test_pause_from_sync(
+    spawn,
+    ctlc: bool,
+):
+    '''
+    Verify we can use the `pdbp` REPL from sync functions AND from
+    any thread spawned with `trio.to_thread.run_sync()`.
+
+    `examples/debugging/sync_bp.py`
+
+    '''
+    child = spawn('sync_bp')
+
+    # first `sync_pause()` after nurseries open
+    child.expect(PROMPT)
+    assert_before(
+        child,
+        [
+            # pre-prompt line
+            _pause_msg,
+            "<Task '__main__.main'",
+            "('root'",
+        ]
+    )
+    if ctlc:
+        do_ctlc(child)
+        # ^NOTE^ subactor not spawned yet; don't need extra delay.
+
+    child.sendline('c')
+
+    # first `await tractor.pause()` inside `p.open_context()` body
+    child.expect(PROMPT)
+
+    # XXX shouldn't see gb loaded message with PDB loglevel!
+    assert not in_prompt_msg(
+        child,
+        ['`greenback` portal opened!'],
+    )
+    # should be same root task
+    assert_before(
+        child,
+        [
+            _pause_msg,
+            "<Task '__main__.main'",
+            "('root'",
+        ]
+    )
+
+    if ctlc:
+        do_ctlc(
+            child,
+            # NOTE: setting this to 0 (or some other sufficient
+            # small val) can cause the test to fail since the
+            # `subactor` suffers a race where the root/parent
+            # sends an actor-cancel prior to it hitting its pause
+            # point; by def the value is 0.1
+            delay=0.4,
+        )
+
+    # XXX, fwiw without a brief sleep here the SIGINT might actually
+    # trigger "subactor" cancellation by its parent  before the
+    # shield-handler is engaged.
+    #
+    # => similar to the `delay` input to `do_ctlc()` below, setting
+    # this too low can cause the test to fail since the `subactor`
+    # suffers a race where the root/parent sends an actor-cancel
+    # prior to the context task hitting its pause point (and thus
+    # engaging the `sigint_shield()` handler in time); this value
+    # seems be good enuf?
+    time.sleep(0.6)
+
+    # one of the bg thread or subactor should have
+    # `Lock.acquire()`-ed
+    # (NOT both, which will result in REPL clobbering!)
+    attach_patts: dict[str, list[str]] = {
+        'subactor': [
+            "'start_n_sync_pause'",
+            "('subactor'",
+        ],
+        'inline_root_bg_thread': [
+            "<Thread(inline_root_bg_thread",
+            "('root'",
+        ],
+        'start_soon_root_bg_thread': [
+            "<Thread(start_soon_root_bg_thread",
+            "('root'",
+        ],
+    }
+    conts: int = 0  # for debugging below matching logic on failure
+    while attach_patts:
+        child.sendline('c')
+        conts += 1
+        child.expect(PROMPT)
+        before = str(child.before.decode())
+        for key in attach_patts:
+            if key in before:
+                attach_key: str = key
+                expected_patts: str = attach_patts.pop(key)
+                assert_before(
+                    child,
+                    [_pause_msg]
+                    +
+                    expected_patts
+                )
+                break
+        else:
+            pytest.fail(
+                f'No keys found?\n\n'
+                f'{attach_patts.keys()}\n\n'
+                f'{before}\n'
+            )
+
+        # ensure no other task/threads engaged a REPL
+        # at the same time as the one that was detected above.
+        for key, other_patts in attach_patts.copy().items():
+            assert not in_prompt_msg(
+                child,
+                other_patts,
+            )
+
+        if ctlc:
+            do_ctlc(
+                child,
+                patt=attach_key,
+                # NOTE same as comment above
+                delay=0.4,
+            )
+
+    child.sendline('c')
+    child.expect(EOF)
+
+
+def expect_any_of(
+    attach_patts: dict[str, list[str]],
+    child,   # what type?
+    ctlc: bool = False,
+    prompt: str = _ctlc_ignore_header,
+    ctlc_delay: float = .4,
+
+) -> list[str]:
+    '''
+    Receive any of a `list[str]` of patterns provided in
+    `attach_patts`.
+
+    Used to test racing prompts from multiple actors and/or
+    tasks using a common root process' `pdbp` REPL.
+
+    '''
+    assert attach_patts
+
+    child.expect(PROMPT)
+    before = str(child.before.decode())
+
+    for attach_key in attach_patts:
+        if attach_key in before:
+            expected_patts: str = attach_patts.pop(attach_key)
+            assert_before(
+                child,
+                expected_patts
+            )
+            break  # from for
+    else:
+        pytest.fail(
+            f'No keys found?\n\n'
+            f'{attach_patts.keys()}\n\n'
+            f'{before}\n'
+        )
+
+    # ensure no other task/threads engaged a REPL
+    # at the same time as the one that was detected above.
+    for key, other_patts in attach_patts.copy().items():
+        assert not in_prompt_msg(
+            child,
+            other_patts,
+        )
+
+    if ctlc:
+        do_ctlc(
+            child,
+            patt=prompt,
+            # NOTE same as comment above
+            delay=ctlc_delay,
+        )
+
+    return expected_patts
+    # yield child
+
+
+def test_pause_from_asyncio_task(
+    spawn,
+    ctlc: bool
+    # ^TODO, fix for `asyncio`!!
+):
+    '''
+    Verify we can use the `pdbp` REPL from an `asyncio.Task` spawned using
+    APIs in `.to_asyncio`.
+
+    `examples/debugging/asycio_bp.py`
+
+    '''
+    child = spawn('asyncio_bp')
+
+    # RACE on whether trio/asyncio task bps first
+    attach_patts: dict[str, list[str]] = {
+
+        # first pause in guest-mode (aka "infecting")
+        # `trio.Task`.
+        'trio-side': [
+            _pause_msg,
+            "<Task 'trio_ctx'",
+            "('aio_daemon'",
+        ],
+
+        # `breakpoint()` from `asyncio.Task`.
+        'asyncio-side': [
+            _pause_msg,
+            "<Task pending name='Task-2' coro=<greenback_shim()",
+            "('aio_daemon'",
+        ],
+    }
+
+    while attach_patts:
+        expect_any_of(
+            attach_patts=attach_patts,
+            child=child,
+            ctlc=ctlc,
+        )
+        child.sendline('c')
+
+    # NOW in race order,
+    # - the asyncio-task will error
+    # - the root-actor parent task will pause
+    #
+    attach_patts: dict[str, list[str]] = {
+
+        # error raised in `asyncio.Task`
+        "raise ValueError('asyncio side error!')": [
+            _crash_msg,
+            'return await chan.receive()',  # `.to_asyncio` impl internals in tb
+            "<Task 'trio_ctx'",
+            "@ ('aio_daemon'",
+            "ValueError: asyncio side error!",
+        ],
+
+        # parent-side propagation via actor-nursery/portal
+        # "tractor._exceptions.RemoteActorError: remote task raised a 'ValueError'": [
+        "remote task raised a 'ValueError'": [
+            _crash_msg,
+            "src_uid=('aio_daemon'",
+            "('aio_daemon'",
+        ],
+
+        # a final pause in root-actor
+        "<Task '__main__.main'": [
+            _pause_msg,
+            "<Task '__main__.main'",
+            "('root'",
+        ],
+    }
+    while attach_patts:
+        expect_any_of(
+            attach_patts=attach_patts,
+            child=child,
+            ctlc=ctlc,
+        )
+        child.sendline('c')
+
+    assert not attach_patts
+
+    # final boxed error propagates to root
+    assert_before(
+        child,
+        [
+            _crash_msg,
+            "<Task '__main__.main'",
+            "('root'",
+            "remote task raised a 'ValueError'",
+            "ValueError: asyncio side error!",
+        ]
+    )
+
+    if ctlc:
+        do_ctlc(
+            child,
+            # NOTE: setting this to 0 (or some other sufficient
+            # small val) can cause the test to fail since the
+            # `subactor` suffers a race where the root/parent
+            # sends an actor-cancel prior to it hitting its pause
+            # point; by def the value is 0.1
+            delay=0.4,
+        )
+
+    child.sendline('c')
+    child.expect(EOF)

tests/test_context_stream_semantics.py

@@ -955,7 +955,7 @@ async def echo_back_sequence(
     )
 
     await ctx.started()
-    # await tractor.breakpoint()
+    # await tractor.pause()
     async with ctx.open_stream(
         msg_buffer_size=msg_buffer_size,
 

tests/test_task_broadcasting.py

@@ -271,7 +271,7 @@ def test_faster_task_to_recv_is_cancelled_by_slower(
                         # the faster subtask was cancelled
                         break
 
-                # await tractor.breakpoint()
+                # await tractor.pause()
                 # await stream.receive()
                 print(f'final value: {value}')
 

tractor/devx/_debug.py

@@ -730,6 +730,9 @@ class DebugStatus:
     # -[ ] see if we can get our proto oco task-mngr to work for
     #   this?
     repl_task: Task|None = None
+    # repl_thread: Thread|None = None
+    # ^TODO?
+
     repl_release: trio.Event|None = None
 
     req_task: Task|None = None
@@ -839,11 +842,12 @@ class DebugStatus:
         if (
             not cls.is_main_trio_thread()
             and
-            # not _state._runtime_vars.get(
+            not _state._runtime_vars.get(
-            #     '_is_infected_aio',
+                '_is_infected_aio',
-            #     False,
+                False,
-            # )
+            )
-            not current_actor().is_infected_aio()
+            # not current_actor().is_infected_aio()
+            # ^XXX, since for bg-thr case will always raise..
         ):
             trio.from_thread.run_sync(
                 signal.signal,
@@ -928,12 +932,27 @@ class DebugStatus:
         try:
             # sometimes the task might already be terminated in
             # which case this call will raise an RTE?
-            if repl_release is not None:
+            # See below for reporting on that..
+            if (
+                repl_release is not None
+                and
+                not repl_release.is_set()
+            ):
                 if cls.is_main_trio_thread():
                     repl_release.set()
 
-                elif current_actor().is_infected_aio():
+                elif (
-
+                    _state._runtime_vars.get(
+                        '_is_infected_aio',
+                        False,
+                    )
+                    # ^XXX, again bc we need to not except
+                    # but for bg-thread case it will always raise..
+                    #
+                    # TODO, is there a better api then using
+                    # `err_on_no_runtime=False` in the below?
+                    # current_actor().is_infected_aio()
+                ):
                     async def _set_repl_release():
                         repl_release.set()
 
@@ -949,6 +968,15 @@ class DebugStatus:
                     trio.from_thread.run_sync(
                         repl_release.set
                     )
+
+        except RuntimeError as rte:
+            log.exception(
+                f'Failed to release debug-request ??\n\n'
+                f'{cls.repr()}\n'
+            )
+            # pdbp.set_trace()
+            raise rte
+
         finally:
             # if req_ctx := cls.req_ctx:
             #     req_ctx._scope.cancel()
@@ -976,9 +1004,10 @@ class DebugStatus:
             #   logging when we don't need to?
             cls.repl = None
 
-            # restore original sigint handler
+            # maybe restore original sigint handler
-            cls.unshield_sigint()
+            # XXX requires runtime check to avoid crash!
-
+            if current_actor(err_on_no_runtime=False):
+                cls.unshield_sigint()
 
 
 # TODO: use the new `@lowlevel.singleton` for this!
@@ -1066,7 +1095,7 @@ class PdbREPL(pdbp.Pdb):
                 # Lock.release(raise_on_thread=False)
                 Lock.release()
 
-            # XXX after `Lock.release()` for root local repl usage
+            # XXX AFTER `Lock.release()` for root local repl usage
             DebugStatus.release()
 
     def set_quit(self):
@@ -1672,7 +1701,7 @@ class DebugRequestError(RuntimeError):
     '''
 
 
-_repl_fail_msg: str = (
+_repl_fail_msg: str|None = (
     'Failed to REPl via `_pause()` '
 )
 
@@ -1712,6 +1741,7 @@ async def _pause(
 
     '''
     __tracebackhide__: bool = hide_tb
+    pause_err: BaseException|None = None
     actor: Actor = current_actor()
     try:
         task: Task = current_task()
@@ -2094,11 +2124,13 @@ async def _pause(
 
     # TODO: prolly factor this plus the similar block from
     # `_enter_repl_sync()` into a common @cm?
-    except BaseException as pause_err:
+    except BaseException as _pause_err:
+        pause_err: BaseException = _pause_err
         if isinstance(pause_err, bdb.BdbQuit):
             log.devx(
-                'REPL for pdb was quit!\n'
+                'REPL for pdb was explicitly quit!\n'
             )
+            _repl_fail_msg = None
 
         # when the actor is mid-runtime cancellation the
         # `Actor._service_n` might get closed before we can spawn
@@ -2117,13 +2149,18 @@ async def _pause(
             )
             return
 
-        else:
+        elif isinstance(pause_err, trio.Cancelled):
-            log.exception(
+            _repl_fail_msg = (
-                _repl_fail_msg
+                'You called `tractor.pause()` from an already cancelled scope!\n\n'
-                +
+                'Consider `await tractor.pause(shield=True)` to make it work B)\n'
-                f'on behalf of {repl_task} ??\n'
             )
 
+        else:
+            _repl_fail_msg += f'on behalf of {repl_task} ??\n'
+
+        if _repl_fail_msg:
+            log.exception(_repl_fail_msg)
+
         if not actor.is_infected_aio():
             DebugStatus.release(cancel_req_task=True)
 
@@ -2152,6 +2189,8 @@ async def _pause(
             DebugStatus.req_err
             or
             repl_err
+            or
+            pause_err
         ):
             __tracebackhide__: bool = False
 
@@ -2435,6 +2474,8 @@ def pause_from_sync(
     called_from_builtin: bool = False,
     api_frame: FrameType|None = None,
 
+    allow_no_runtime: bool = False,
+
     # proxy to `._pause()`, for ex:
     # shield: bool = False,
     # api_frame: FrameType|None = None,
@@ -2453,16 +2494,25 @@ def pause_from_sync(
 
     '''
     __tracebackhide__: bool = hide_tb
+    repl_owner: Task|Thread|None = None
     try:
         actor: tractor.Actor = current_actor(
             err_on_no_runtime=False,
         )
-        if not actor:
+        if (
-            raise RuntimeError(
+            not actor
-                'Not inside the `tractor`-runtime?\n'
+            and
+            not allow_no_runtime
+        ):
+            raise NoRuntime(
+                'The actor runtime has not been opened?\n\n'
                 '`tractor.pause_from_sync()` is not functional without a wrapping\n'
                 '- `async with tractor.open_nursery()` or,\n'
-                '- `async with tractor.open_root_actor()`\n'
+                '- `async with tractor.open_root_actor()`\n\n'
+
+                'If you are getting this from a builtin `breakpoint()` call\n'
+                'it might mean the runtime was started then '
+                'stopped prematurely?\n'
             )
         message: str = (
             f'{actor.uid} task called `tractor.pause_from_sync()`\n'
@@ -2485,6 +2535,7 @@ def pause_from_sync(
         repl: PdbREPL = mk_pdb()
 
         # message += f'-> created local REPL {repl}\n'
+        is_trio_thread: bool = DebugStatus.is_main_trio_thread()
         is_root: bool = is_root_process()
         is_aio: bool = actor.is_infected_aio()
 
@@ -2500,7 +2551,7 @@ def pause_from_sync(
         # thread which will call `._pause()` manually with special
         # handling for root-actor caller usage.
         if (
-            not DebugStatus.is_main_trio_thread()
+            not is_trio_thread
             and
             not is_aio  # see below for this usage
         ):
@@ -2574,7 +2625,11 @@ def pause_from_sync(
                 DebugStatus.shield_sigint()
                 assert bg_task is not DebugStatus.repl_task
 
-        elif is_aio:
+        elif (
+            not is_trio_thread
+            and
+            is_aio
+        ):
             greenback: ModuleType = maybe_import_greenback()
             repl_owner: Task = asyncio.current_task()
             DebugStatus.shield_sigint()
@@ -2758,9 +2813,11 @@ def _post_mortem(
         # ^TODO, instead a nice runtime-info + maddr + uid?
         # -[ ] impl a `Actor.__repr()__`??
         #  |_ <task>:<thread> @ <actor>
+        # no_runtime: bool = False
 
     except NoRuntime:
         actor_repr: str = '<no-actor-runtime?>'
+        # no_runtime: bool = True
 
     try:
         task_repr: Task = current_task()
@@ -2796,6 +2853,8 @@ def _post_mortem(
     # Since we presume the post-mortem was enaged to a task-ending
     # error, we MUST release the local REPL request so that not other
     # local task nor the root remains blocked!
+    # if not no_runtime:
+    #     DebugStatus.release()
     DebugStatus.release()
 
 
@@ -3033,6 +3092,7 @@ async def maybe_wait_for_debugger(
     #         pass
     return False
 
+
 # TODO: better naming and what additionals?
 # - [ ] optional runtime plugging?
 # - [ ] detection for sync vs. async code?