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tractor
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Merge pull request #42 from tgoodlet/improved_errors 

Improved errors - introduce trio.MultiError
loglevel_to_tractor_tests
goodboy 2018-11-22 14:56:11 -05:00 committed by GitHub
parent 469a1e5874 23c7519fec
commit b0f7e6a954
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GPG Key ID: 4AEE18F83AFDEB23
8 changed files with 367 additions and 148 deletions
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108
tests/test_cancellation.py
View File

@ -14,26 +14,66 @@ async def assert_err():
assert 0
def test_remote_error(arb_addr):
"""Verify an error raises in a subactor is propagated to the parent.
@pytest.mark.parametrize(
'args_err',
[
# expected to be thrown in assert_err
({}, AssertionError),
# argument mismatch raised in _invoke()
({'unexpected': 10}, TypeError)
],
ids=['no_args', 'unexpected_args'],
)
def test_remote_error(arb_addr, args_err):
"""Verify an error raised in a subactor that is propagated
to the parent nursery, contains the underlying boxed builtin
error type info and causes cancellation and reraising all the
way up the stack.
"""
args, errtype = args_err
async def main():
async with tractor.open_nursery() as nursery:
portal = await nursery.run_in_actor('errorer', assert_err, **args)
# get result(s) from main task
try:
await portal.result()
except tractor.RemoteActorError as err:
assert err.type == errtype
print("Look Maa that actor failed hard, hehh")
raise
with pytest.raises(tractor.RemoteActorError) as excinfo:
tractor.run(main, arbiter_addr=arb_addr)
# ensure boxed error is correct
assert excinfo.value.type == errtype
def test_multierror(arb_addr):
"""Verify we raise a ``trio.MultiError`` out of a nursery where
more then one actor errors.
"""
async def main():
async with tractor.open_nursery() as nursery:
portal = await nursery.run_in_actor('errorer', assert_err)
await nursery.run_in_actor('errorer1', assert_err)
portal2 = await nursery.run_in_actor('errorer2', assert_err)
# get result(s) from main task
try:
return await portal.result()
except tractor.RemoteActorError:
print("Look Maa that actor failed hard, hehh")
await portal2.result()
except tractor.RemoteActorError as err:
assert err.type == AssertionError
print("Look Maa that first actor failed hard, hehh")
raise
except Exception:
pass
assert 0, "Remote error was not raised?"
with pytest.raises(tractor.RemoteActorError):
# also raises
# here we should get a `trio.MultiError` containing exceptions
# from both subactors
with pytest.raises(trio.MultiError):
tractor.run(main, arbiter_addr=arb_addr)
@ -42,9 +82,12 @@ def do_nothing():
def test_cancel_single_subactor(arb_addr):
async def main():
"""Ensure a ``ActorNursery.start_actor()`` spawned subactor
cancels when the nursery is cancelled.
"""
async def spawn_actor():
"""Spawn an actor that blocks indefinitely.
"""
async with tractor.open_nursery() as nursery:
portal = await nursery.start_actor(
@ -55,7 +98,7 @@ def test_cancel_single_subactor(arb_addr):
# would hang otherwise
await nursery.cancel()
tractor.run(main, arbiter_addr=arb_addr)
tractor.run(spawn_actor, arbiter_addr=arb_addr)
async def stream_forever():
@ -87,13 +130,22 @@ async def test_cancel_infinite_streamer():
assert n.cancelled
@pytest.mark.parametrize(
'num_actors_and_errs',
[
(1, tractor.RemoteActorError, AssertionError),
(2, tractor.MultiError, AssertionError)
],
ids=['one_actor', 'two_actors'],
)
@tractor_test
async def test_one_cancels_all():
"""Verify one failed actor causes all others in the nursery
to be cancelled just like in trio.
async def test_some_cancels_all(num_actors_and_errs):
"""Verify a subset of failed subactors causes all others in
the nursery to be cancelled just like the strategy in trio.
This is the first and only supervisory strategy at the moment.
"""
num, first_err, err_type = num_actors_and_errs
try:
async with tractor.open_nursery() as n:
real_actors = []
@ -103,13 +155,23 @@ async def test_one_cancels_all():
rpc_module_paths=[__name__],
))
# start one actor that will fail immediately
await n.run_in_actor('extra', assert_err)
for i in range(num):
# start actor(s) that will fail immediately
await n.run_in_actor(f'extra_{i}', assert_err)
# should error here with a ``RemoteActorError`` containing
# an ``AssertionError`
# should error here with a ``RemoteActorError`` or ``MultiError``
except first_err as err:
if isinstance(err, tractor.MultiError):
assert len(err.exceptions) == num
for exc in err.exceptions:
if isinstance(exc, tractor.RemoteActorError):
assert exc.type == err_type
else:
assert isinstance(exc, trio.Cancelled)
elif isinstance(err, tractor.RemoteActorError):
assert err.type == err_type
except tractor.RemoteActorError:
assert n.cancelled is True
assert not n._children
else:

2
tests/test_multi_program.py
View File

@ -41,7 +41,7 @@ def daemon(loglevel, testdir, arb_addr):
stderr=subprocess.PIPE,
)
assert not proc.returncode
wait = 0.6 if sys.version_info < (3, 7) else 0.2
wait = 0.6 if sys.version_info < (3, 7) else 0.4
time.sleep(wait)
yield proc
sig_prog(proc, signal.SIGINT)

2
tests/test_streaming.py
View File

@ -166,7 +166,7 @@ def test_a_quadruple_example(time_quad_ex):
@pytest.mark.parametrize(
'cancel_delay',
list(map(lambda i: i/10, range(2, 8)))
list(map(lambda i: i/10, range(3, 9)))
)
def test_not_fast_enough_quad(arb_addr, time_quad_ex, cancel_delay):
"""Verify we can cancel midway through the quad example and all actors

10
tractor/__init__.py
View File

@ -4,10 +4,11 @@ tractor: An actor model micro-framework built on
"""
import importlib
from functools import partial
from typing import Tuple, Any, Optional
from typing import Tuple, Any
import typing
import trio # type: ignore
from trio import MultiError
from .log import get_console_log, get_logger, get_loglevel
from ._ipc import _connect_chan, Channel
@ -16,17 +17,18 @@ from ._actor import (
)
from ._trionics import open_nursery
from ._state import current_actor
from ._portal import RemoteActorError
from ._exceptions import RemoteActorError
__all__ = [
'current_actor',
'find_actor',
'get_arbiter',
'wait_for_actor',
'open_nursery',
'RemoteActorError',
'wait_for_actor',
'Channel',
'MultiError',
'RemoteActorError',
]

82
tractor/_actor.py
View File

@ -16,6 +16,7 @@ from async_generator import asynccontextmanager, aclosing
from ._ipc import Channel, _connect_chan
from .log import get_console_log, get_logger
from ._exceptions import pack_error, InternalActorError
from ._portal import (
Portal,
open_portal,
@ -33,10 +34,6 @@ class ActorFailure(Exception):
"General actor failure"
class InternalActorError(RuntimeError):
"Actor primitive internals failure"
async def _invoke(
actor: 'Actor',
cid: str,
@ -49,6 +46,7 @@ async def _invoke(
"""
sig = inspect.signature(func)
treat_as_gen = False
cs = None
if 'chan' in sig.parameters:
assert 'cid' in sig.parameters, \
f"{func} must accept a `cid` (caller id) kwarg"
@ -122,10 +120,19 @@ async def _invoke(
with trio.open_cancel_scope() as cs:
task_status.started(cs)
await chan.send({'return': await coro, 'cid': cid})
except Exception:
except Exception as err:
# always ship errors back to caller
log.exception("Actor errored:")
await chan.send({'error': traceback.format_exc(), 'cid': cid})
err_msg = pack_error(err)
err_msg['cid'] = cid
try:
await chan.send(err_msg)
except trio.ClosedResourceError:
log.exception(
f"Failed to ship error to caller @ {chan.uid}")
if cs is None:
# error is from above code not from rpc invocation
task_status.started(err)
finally:
# RPC task bookeeping
tasks = actor._rpc_tasks.get(chan, None)
@ -348,13 +355,19 @@ class Actor:
try:
ns, funcname, kwargs, actorid, cid = msg['cmd']
except KeyError:
# push any non-rpc-response error to all local consumers
# and mark the channel as errored
chan._exc = err = msg['error']
# This is the non-rpc error case, that is, an
# error **not** raised inside a call to ``_invoke()``
# (i.e. no cid was provided in the msg - see above).
# Push this error to all local channel consumers
# (normally portals) by marking the channel as errored
tb_str = msg.get('tb_str')
assert chan.uid
for cid in self._actors2calls[chan.uid]:
await self._push_result(chan.uid, cid, msg)
raise InternalActorError(f"{chan.uid}\n" + err)
exc = InternalActorError(
f"{chan.uid}\n" + tb_str,
**msg,
)
chan._exc = exc
raise exc
log.debug(
f"Processing request from {actorid}\n"
@ -373,22 +386,30 @@ class Actor:
# never allow cancelling cancel requests (results in
# deadlock and other weird behaviour)
if func != self.cancel:
self._no_more_rpc_tasks.clear()
log.info(f"RPC func is {func}")
self._rpc_tasks.setdefault(chan, []).append((cs, func))
if isinstance(cs, Exception):
log.warn(f"Task for RPC func {func} failed with {cs}")
else:
# mark that we have ongoing rpc tasks
self._no_more_rpc_tasks.clear()
log.info(f"RPC func is {func}")
# store cancel scope such that the rpc task can be
# cancelled gracefully if requested
self._rpc_tasks.setdefault(chan, []).append((cs, func))
log.debug(
f"Waiting on next msg for {chan} from {chan.uid}")
else: # channel disconnect
else:
# channel disconnect
log.debug(f"{chan} from {chan.uid} disconnected")
except trio.ClosedResourceError:
log.error(f"{chan} form {chan.uid} broke")
except Exception:
# ship exception (from above code) to parent
except Exception as err:
# ship any "internal" exception (i.e. one from internal machinery
# not from an rpc task) to parent
log.exception("Actor errored:")
if self._parent_chan:
await self._parent_chan.send({'error': traceback.format_exc()})
raise
await self._parent_chan.send(pack_error(err))
raise
# if this is the `MainProcess` we expect the error broadcasting
# above to trigger an error at consuming portal "checkpoints"
finally:
@ -480,25 +501,30 @@ class Actor:
# blocks here as expected until the channel server is
# killed (i.e. this actor is cancelled or signalled by the parent)
except Exception:
except Exception as err:
if not registered_with_arbiter:
log.exception(
f"Actor errored and failed to register with arbiter "
f"@ {arbiter_addr}")
if self._parent_chan:
try:
# internal error so ship to parent without cid
await self._parent_chan.send(
{'error': traceback.format_exc()})
pack_error(err))
except trio.ClosedResourceError:
log.error(
f"Failed to ship error to parent "
f"{self._parent_chan.uid}, channel was closed")
log.exception("Actor errored:")
if not registered_with_arbiter:
log.exception(
f"Actor errored and failed to register with arbiter "
f"@ {arbiter_addr}")
else:
# XXX wait, why?
# causes a hang if I always raise..
raise
finally:
await self._do_unreg(arbiter_addr)
if registered_with_arbiter:
await self._do_unreg(arbiter_addr)
# terminate actor once all it's peers (actors that connected
# to it as clients) have disappeared
if not self._no_more_peers.is_set():

50
tractor/_exceptions.py 100644
View File

@ -0,0 +1,50 @@
"""
Our classy exception set.
"""
import builtins
import traceback
class RemoteActorError(Exception):
# TODO: local recontruction of remote exception deats
"Remote actor exception bundled locally"
def __init__(self, message, type_str, **msgdata):
super().__init__(message)
self.type = getattr(builtins, type_str, Exception)
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
failure of some primitive or machinery.
"""
class NoResult(RuntimeError):
"No final result is expected for this actor"
def pack_error(exc):
"""Create an "error message" for tranmission over
a channel (aka the wire).
"""
return {
'error': {
'tb_str': traceback.format_exc(),
'type_str': type(exc).__name__,
}
}
def unpack_error(msg, chan=None):
"""Unpack an 'error' message from the wire
into a local ``RemoteActorError``.
"""
tb_str = msg['error'].get('tb_str', '')
return RemoteActorError(
f"{chan.uid}\n" + tb_str,
**msg['error'],
)

75
tractor/_portal.py
View File

@ -12,15 +12,12 @@ from async_generator import asynccontextmanager
from ._state import current_actor
from ._ipc import Channel
from .log import get_logger
from ._exceptions import unpack_error, NoResult, RemoteActorError
log = get_logger('tractor')
class RemoteActorError(RuntimeError):
"Remote actor exception bundled locally"
@asynccontextmanager
async def maybe_open_nursery(nursery: trio._core._run.Nursery = None):
"""Create a new nursery if None provided.
@ -63,8 +60,8 @@ class Portal:
# when this is set to a tuple returned from ``_submit()`` then
# it is expected that ``result()`` will be awaited at some point
# during the portal's lifetime
self._result = None
self._exc: Optional[RemoteActorError] = None
self._result: Optional[Any] = None
# set when _submit_for_result is called
self._expect_result: Optional[
Tuple[str, Any, str, Dict[str, Any]]
] = None
@ -97,8 +94,7 @@ class Portal:
elif functype == 'asyncgen':
resp_type = 'yield'
elif 'error' in first_msg:
raise RemoteActorError(
f"{self.channel.uid}\n" + first_msg['error'])
raise unpack_error(first_msg, self.channel)
else:
raise ValueError(f"{first_msg} is an invalid response packet?")
@ -110,10 +106,11 @@ class Portal:
self._expect_result = await self._submit(ns, func, **kwargs)
async def run(self, ns: str, func: str, **kwargs) -> Any:
"""Submit a function to be scheduled and run by actor, wrap and return
its (stream of) result(s).
"""Submit a remote function to be scheduled and run by actor,
wrap and return its (stream of) result(s).
This is a blocking call.
This is a blocking call and returns either a value from the
remote rpc task or a local async generator instance.
"""
return await self._return_from_resptype(
*(await self._submit(ns, func, **kwargs))
@ -137,14 +134,19 @@ class Portal:
if 'stop' in msg:
break # far end async gen terminated
else:
raise RemoteActorError(
f"{self.channel.uid}\n" + msg['error'])
# internal error should never get here
assert msg.get('cid'), (
"Received internal error at portal?")
raise unpack_error(msg, self.channel)
except StopAsyncIteration:
log.debug(
f"Cancelling async gen call {cid} to "
f"{self.channel.uid}")
raise
# TODO: use AsyncExitStack to aclose() all agens
# on teardown
return yield_from_q()
elif resptype == 'return':
@ -152,30 +154,43 @@ class Portal:
try:
return msg['return']
except KeyError:
self._exc = RemoteActorError(
f"{self.channel.uid}\n" + msg['error'])
raise self._exc
# internal error should never get here
assert msg.get('cid'), "Received internal error at portal?"
raise unpack_error(msg, self.channel)
else:
raise ValueError(f"Unknown msg response type: {first_msg}")
async def result(self) -> Any:
"""Return the result(s) from the remote actor's "main" task.
"""
if self._expect_result is None:
# (remote) errors are slapped on the channel
# teardown can reraise them
exc = self.channel._exc
if exc:
raise RemoteActorError(f"{self.channel.uid}\n{exc}")
else:
raise RuntimeError(
f"Portal for {self.channel.uid} is not expecting a final"
"result?")
# Check for non-rpc errors slapped on the
# channel for which we always raise
exc = self.channel._exc
if exc:
raise exc
# not expecting a "main" result
if self._expect_result is None:
log.warn(
f"Portal for {self.channel.uid} not expecting a final"
" result?\nresult() should only be called if subactor"
" was spawned with `ActorNursery.run_in_actor()`")
return NoResult
# expecting a "main" result
assert self._expect_result
if self._result is None:
try:
self._result = await self._return_from_resptype(
*self._expect_result
)
except RemoteActorError as err:
self._result = err
# re-raise error on every call
if isinstance(self._result, RemoteActorError):
raise self._result
elif self._result is None:
self._result = await self._return_from_resptype(
*self._expect_result
)
return self._result
async def close(self) -> None:

186
tractor/_trionics.py
View File

@ -32,7 +32,8 @@ class ActorNursery:
Tuple[str, str],
Tuple[Actor, mp.Process, Optional[Portal]]
] = {}
# portals spawned with ``run_in_actor()``
# portals spawned with ``run_in_actor()`` are
# cancelled when their "main" result arrives
self._cancel_after_result_on_exit: set = set()
self.cancelled: bool = False
self._forkserver: forkserver.ForkServer = None
@ -132,6 +133,8 @@ class ActorNursery:
bind_addr=bind_addr,
statespace=statespace,
)
# this marks the actor to be cancelled after its portal result
# is retreived, see ``wait()`` below.
self._cancel_after_result_on_exit.add(portal)
await portal._submit_for_result(
mod_path,
@ -142,29 +145,66 @@ class ActorNursery:
async def wait(self) -> None:
"""Wait for all subactors to complete.
This is probably the most complicated (and confusing, sorry)
function that does all the clever crap to deal with cancellation,
error propagation, and graceful subprocess tear down.
"""
async def maybe_consume_result(portal, actor):
if (
portal in self._cancel_after_result_on_exit and
(portal._result is None and portal._exc is None)
):
log.debug(f"Waiting on final result from {subactor.uid}")
res = await portal.result()
# if it's an async-gen then we should alert the user
# that we're cancelling it
async def exhaust_portal(portal, actor):
"""Pull final result from portal (assuming it has one).
If the main task is an async generator do our best to consume
what's left of it.
"""
try:
log.debug(f"Waiting on final result from {actor.uid}")
final = res = await portal.result()
# if it's an async-gen then alert that we're cancelling it
if inspect.isasyncgen(res):
final = []
log.warning(
f"Blindly consuming asyncgen for {actor.uid}")
with trio.fail_after(1):
async with aclosing(res) as agen:
async for item in agen:
log.debug(f"Consuming item {item}")
final.append(item)
except (Exception, trio.MultiError) as err:
# we reraise in the parent task via a ``trio.MultiError``
return err
else:
return final
async def cancel_on_completion(
portal: Portal,
actor: Actor,
task_status=trio.TASK_STATUS_IGNORED,
) -> None:
"""Cancel actor gracefully once it's "main" portal's
result arrives.
Should only be called for actors spawned with `run_in_actor()`.
"""
with trio.open_cancel_scope() as cs:
task_status.started(cs)
# 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
result = await exhaust_portal(portal, actor)
if isinstance(result, Exception):
errors.append(result)
log.info(f"Cancelling {portal.channel.uid} gracefully")
await portal.cancel_actor()
if cs.cancelled_caught:
log.warning(
"Result waiter was cancelled, process may have died")
async def wait_for_proc(
proc: mp.Process,
actor: Actor,
portal: Portal,
cancel_scope: trio._core._run.CancelScope,
cancel_scope: Optional[trio._core._run.CancelScope] = None,
) -> None:
# TODO: timeout block here?
if proc.is_alive():
@ -172,42 +212,59 @@ class ActorNursery:
# please god don't hang
proc.join()
log.debug(f"Joined {proc}")
await maybe_consume_result(portal, actor)
self._children.pop(actor.uid)
# proc terminated, cancel result waiter
# proc terminated, cancel result waiter that may have
# been spawned in tandem
if cancel_scope:
log.warning(
f"Cancelling existing result waiter task for {actor.uid}")
cancel_scope.cancel()
async def wait_for_actor(
portal: Portal,
actor: Actor,
task_status=trio.TASK_STATUS_IGNORED,
) -> None:
# cancel the actor gracefully
with trio.open_cancel_scope() as cs:
task_status.started(cs)
await maybe_consume_result(portal, actor)
log.info(f"Cancelling {portal.channel.uid} gracefully")
await portal.cancel_actor()
if cs.cancelled_caught:
log.warning("Result waiter was cancelled")
# unblocks when all waiter tasks have completed
log.debug(f"Waiting on all subactors to complete")
# since we pop each child subactor on termination,
# iterate a copy
children = self._children.copy()
errors: List[Exception] = []
# wait on run_in_actor() tasks, unblocks when all complete
async with trio.open_nursery() as nursery:
for subactor, proc, portal in children.values():
cs = None
# portal from ``run_in_actor()``
if portal in self._cancel_after_result_on_exit:
cs = await nursery.start(wait_for_actor, portal, subactor)
cs = await nursery.start(
cancel_on_completion, portal, subactor)
# TODO: how do we handle remote host spawned actors?
nursery.start_soon(
wait_for_proc, proc, subactor, portal, cs)
if errors:
if not self.cancelled:
# halt here and expect to be called again once the nursery
# has been cancelled externally (ex. from within __aexit__()
# if an error is captured from ``wait()`` then ``cancel()``
# is called immediately after which in turn calls ``wait()``
# again.)
raise trio.MultiError(errors)
# wait on all `start_actor()` subactors to complete
# if errors were captured above and we have not been cancelled
# then these ``start_actor()`` spawned actors will block until
# cancelled externally
children = self._children.copy()
async with trio.open_nursery() as nursery:
for subactor, proc, portal in children.values():
# TODO: how do we handle remote host spawned actors?
nursery.start_soon(wait_for_proc, proc, subactor, portal, cs)
log.debug(f"All subactors for {self} have terminated")
if errors:
# always raise any error if we're also cancelled
raise trio.MultiError(errors)
async def cancel(self, hard_kill: bool = False) -> None:
"""Cancel this nursery by instructing each subactor to cancel
iteslf and wait for all subprocesses to terminate.
itself and wait for all subactors to terminate.
If ``hard_killl`` is set to ``True`` then kill the processes
directly without any far end graceful ``trio`` cancellation.
@ -234,56 +291,57 @@ class ActorNursery:
# channel/portal should now be up
_, _, portal = self._children[subactor.uid]
if portal is None:
# cancelled while waiting on the event?
# cancelled while waiting on the event
# to arrive
chan = self._actor._peers[subactor.uid][-1]
if chan:
portal = Portal(chan)
else: # there's no other choice left
do_hard_kill(proc)
# spawn cancel tasks async
# spawn cancel tasks
assert portal
n.start_soon(portal.cancel_actor)
log.debug(f"Waiting on all subactors to complete")
await self.wait()
# mark ourselves as having (tried to have) cancelled all subactors
self.cancelled = True
log.debug(f"All subactors for {self} have terminated")
await self.wait()
async def __aexit__(self, etype, value, tb):
"""Wait on all subactor's main routines to complete.
"""
try:
if etype is not None:
if etype is not None:
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? Should both be shielded?
# a cancel signal shows up slightly after in which case
# the `else:` block here might not complete?
# For now, shield both.
with trio.open_cancel_scope(shield=True):
if etype is trio.Cancelled:
log.warning(
f"{current_actor().uid} was cancelled with {etype}"
", cancelling actor nursery")
await self.cancel()
f"Nursery for {current_actor().uid} was "
f"cancelled with {etype}")
else:
log.exception(
f"{current_actor().uid} errored with {etype}, "
"cancelling actor nursery")
await self.cancel()
else:
# XXX: this is effectively the lone cancellation/supervisor
# strategy which exactly mimicks trio's behaviour
log.debug(f"Waiting on subactors {self._children} to complete")
try:
await self.wait()
except Exception as err:
log.warning(f"Nursery caught {err}, cancelling")
f"Nursery for {current_actor().uid} "
f"errored with {etype}, ")
await self.cancel()
raise
log.debug(f"Nursery teardown complete")
except Exception:
log.exception("Error on nursery exit:")
await self.wait()
raise
except trio.MultiError as merr:
if value not in merr.exceptions:
raise trio.MultiError(merr.exceptions + [value])
raise
else:
# XXX: this is effectively the (for now) lone
# cancellation/supervisor strategy which exactly
# mimicks trio's behaviour
log.debug(f"Waiting on subactors {self._children} to complete")
try:
await self.wait()
except (Exception, trio.MultiError) as err:
log.warning(f"Nursery caught {err}, cancelling")
await self.cancel()
raise
log.debug(f"Nursery teardown complete")
@asynccontextmanager
@ -297,3 +355,9 @@ async def open_nursery() -> typing.AsyncGenerator[ActorNursery, None]:
# TODO: figure out supervisors from erlang
async with ActorNursery(current_actor()) as nursery:
yield nursery
def is_main_process():
"""Bool determining if this actor is running in the top-most process.
"""
return mp.current_process().name == 'MainProcess'