482 lines
16 KiB
Python
482 lines
16 KiB
Python
"""
|
|
Machinery for actor process spawning using multiple backends.
|
|
"""
|
|
import sys
|
|
import multiprocessing as mp
|
|
import platform
|
|
from typing import Any, Dict, Optional
|
|
|
|
import trio
|
|
from trio_typing import TaskStatus
|
|
from async_generator import asynccontextmanager
|
|
|
|
try:
|
|
from multiprocessing import semaphore_tracker # type: ignore
|
|
resource_tracker = semaphore_tracker
|
|
resource_tracker._resource_tracker = resource_tracker._semaphore_tracker
|
|
except ImportError:
|
|
# 3.8 introduces a more general version that also tracks shared mems
|
|
from multiprocessing import resource_tracker # type: ignore
|
|
|
|
from multiprocessing import forkserver # type: ignore
|
|
from typing import Tuple
|
|
|
|
from . import _forkserver_override
|
|
from ._state import (
|
|
current_actor,
|
|
is_main_process,
|
|
)
|
|
|
|
from .log import get_logger
|
|
from ._portal import Portal
|
|
from ._actor import Actor, ActorFailure
|
|
from ._entry import _mp_main
|
|
|
|
|
|
log = get_logger('tractor')
|
|
|
|
# placeholder for an mp start context if so using that backend
|
|
_ctx: Optional[mp.context.BaseContext] = None
|
|
_spawn_method: str = "spawn"
|
|
|
|
|
|
if platform.system() == 'Windows':
|
|
_spawn_method = "spawn"
|
|
_ctx = mp.get_context("spawn")
|
|
|
|
async def proc_waiter(proc: mp.Process) -> None:
|
|
await trio.lowlevel.WaitForSingleObject(proc.sentinel)
|
|
else:
|
|
# *NIX systems use ``trio`` primitives as our default
|
|
_spawn_method = "trio"
|
|
|
|
async def proc_waiter(proc: mp.Process) -> None:
|
|
await trio.lowlevel.wait_readable(proc.sentinel)
|
|
|
|
|
|
def try_set_start_method(name: str) -> Optional[mp.context.BaseContext]:
|
|
"""Attempt to set the method for process starting, aka the "actor
|
|
spawning backend".
|
|
|
|
If the desired method is not supported this function will error.
|
|
On Windows only the ``multiprocessing`` "spawn" method is offered
|
|
besides the default ``trio`` which uses async wrapping around
|
|
``subprocess.Popen``.
|
|
"""
|
|
global _ctx
|
|
global _spawn_method
|
|
|
|
methods = mp.get_all_start_methods()
|
|
if 'fork' in methods:
|
|
# forking is incompatible with ``trio``s global task tree
|
|
methods.remove('fork')
|
|
|
|
# supported on all platforms
|
|
methods += ['trio']
|
|
|
|
if name not in methods:
|
|
raise ValueError(
|
|
f"Spawn method `{name}` is invalid please choose one of {methods}"
|
|
)
|
|
elif name == 'forkserver':
|
|
_forkserver_override.override_stdlib()
|
|
_ctx = mp.get_context(name)
|
|
elif name == 'trio':
|
|
_ctx = None
|
|
else:
|
|
_ctx = mp.get_context(name)
|
|
|
|
_spawn_method = name
|
|
return _ctx
|
|
|
|
|
|
async def exhaust_portal(
|
|
portal: Portal,
|
|
actor: Actor
|
|
) -> Any:
|
|
"""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}")
|
|
|
|
# XXX: streams should never be reaped here since they should
|
|
# always be established and shutdown using a context manager api
|
|
final = await portal.result()
|
|
|
|
except (Exception, trio.MultiError) as err:
|
|
# we reraise in the parent task via a ``trio.MultiError``
|
|
return err
|
|
except trio.Cancelled as err:
|
|
# lol, of course we need this too ;P
|
|
# TODO: merge with above?
|
|
log.warning(f"Cancelled result waiter for {portal.actor.uid}")
|
|
return err
|
|
else:
|
|
log.debug(f"Returning final result: {final}")
|
|
return final
|
|
|
|
|
|
async def cancel_on_completion(
|
|
portal: Portal,
|
|
actor: Actor,
|
|
errors: Dict[Tuple[str, str], Exception],
|
|
task_status: TaskStatus[trio.CancelScope] = 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.CancelScope() 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[actor.uid] = result
|
|
log.warning(
|
|
f"Cancelling {portal.channel.uid} after error {result}"
|
|
)
|
|
|
|
else:
|
|
log.runtime(
|
|
f"Cancelling {portal.channel.uid} gracefully "
|
|
f"after result {result}")
|
|
|
|
# cancel the process now that we have a final result
|
|
await portal.cancel_actor()
|
|
|
|
|
|
async def do_hard_kill(
|
|
proc: trio.Process,
|
|
) -> 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.
|
|
with trio.move_on_after(3) as cs:
|
|
|
|
# NOTE: This ``__aexit__()`` shields internally.
|
|
async with proc: # calls ``trio.Process.aclose()``
|
|
log.debug(f"Terminating {proc}")
|
|
|
|
if cs.cancelled_caught:
|
|
# XXX: should pretty much never get here unless we have
|
|
# to move the bits from ``proc.__aexit__()`` out and
|
|
# into here.
|
|
log.critical(f"HARD KILLING {proc}")
|
|
proc.kill()
|
|
|
|
|
|
@asynccontextmanager
|
|
async def spawn_subactor(
|
|
subactor: 'Actor',
|
|
parent_addr: Tuple[str, int],
|
|
):
|
|
spawn_cmd = [
|
|
sys.executable,
|
|
"-m",
|
|
# Hardcode this (instead of using ``_child.__name__`` to avoid a
|
|
# double import warning: https://stackoverflow.com/a/45070583
|
|
"tractor._child",
|
|
# We provide the child's unique identifier on this exec/spawn
|
|
# line for debugging purposes when viewing the process tree from
|
|
# the OS; it otherwise can be passed via the parent channel if
|
|
# we prefer in the future (for privacy).
|
|
"--uid",
|
|
str(subactor.uid),
|
|
# Address the child must connect to on startup
|
|
"--parent_addr",
|
|
str(parent_addr)
|
|
]
|
|
|
|
if subactor.loglevel:
|
|
spawn_cmd += [
|
|
"--loglevel",
|
|
subactor.loglevel
|
|
]
|
|
|
|
proc = await trio.open_process(spawn_cmd)
|
|
try:
|
|
yield proc
|
|
|
|
finally:
|
|
log.runtime(f"Attempting to kill {proc}")
|
|
|
|
# XXX: do this **after** cancellation/tearfown
|
|
# to avoid killing the process too early
|
|
# since trio does this internally on ``__aexit__()``
|
|
|
|
await do_hard_kill(proc)
|
|
|
|
|
|
async def new_proc(
|
|
name: str,
|
|
actor_nursery: 'ActorNursery', # type: ignore # noqa
|
|
subactor: Actor,
|
|
errors: Dict[Tuple[str, str], Exception],
|
|
# passed through to actor main
|
|
bind_addr: Tuple[str, int],
|
|
parent_addr: Tuple[str, int],
|
|
_runtime_vars: Dict[str, Any], # serialized and sent to _child
|
|
*,
|
|
task_status: TaskStatus[Portal] = trio.TASK_STATUS_IGNORED
|
|
) -> None:
|
|
"""Create a new ``multiprocessing.Process`` using the
|
|
spawn method as configured using ``try_set_start_method()``.
|
|
"""
|
|
cancel_scope = None
|
|
|
|
# mark the new actor with the global spawn method
|
|
subactor._spawn_method = _spawn_method
|
|
|
|
if _spawn_method == 'trio':
|
|
async with trio.open_nursery() as nursery:
|
|
async with spawn_subactor(
|
|
subactor,
|
|
parent_addr,
|
|
) as proc:
|
|
log.runtime(f"Started {proc}")
|
|
|
|
# wait for actor to spawn and connect back to us
|
|
# channel should have handshake completed by the
|
|
# local actor by the time we get a ref to it
|
|
event, chan = await actor_nursery._actor.wait_for_peer(
|
|
subactor.uid)
|
|
portal = Portal(chan)
|
|
actor_nursery._children[subactor.uid] = (
|
|
subactor, proc, portal)
|
|
|
|
# send additional init params
|
|
await chan.send({
|
|
"_parent_main_data": subactor._parent_main_data,
|
|
"enable_modules": subactor.enable_modules,
|
|
"_arb_addr": subactor._arb_addr,
|
|
"bind_host": bind_addr[0],
|
|
"bind_port": bind_addr[1],
|
|
"_runtime_vars": _runtime_vars,
|
|
})
|
|
|
|
# track subactor in current nursery
|
|
curr_actor = current_actor()
|
|
curr_actor._actoruid2nursery[subactor.uid] = actor_nursery
|
|
|
|
# resume caller at next checkpoint now that child is up
|
|
task_status.started(portal)
|
|
|
|
# wait for ActorNursery.wait() to be called
|
|
with trio.CancelScope(shield=True):
|
|
await actor_nursery._join_procs.wait()
|
|
|
|
if portal in actor_nursery._cancel_after_result_on_exit:
|
|
cancel_scope = await nursery.start(
|
|
cancel_on_completion,
|
|
portal,
|
|
subactor,
|
|
errors
|
|
)
|
|
|
|
# Wait for proc termination but **dont' yet** call
|
|
# ``trio.Process.__aexit__()`` (it tears down stdio
|
|
# which will kill any waiting remote pdb trace).
|
|
|
|
# TODO: No idea how we can enforce zombie
|
|
# reaping more stringently without the shield
|
|
# we used to have below...
|
|
|
|
# with trio.CancelScope(shield=True):
|
|
# async with proc:
|
|
|
|
# Always "hard" join sub procs since no actor zombies
|
|
# are allowed!
|
|
|
|
# this is a "light" (cancellable) join, the hard join is
|
|
# in the enclosing scope (see above).
|
|
await proc.wait()
|
|
|
|
log.debug(f"Joined {proc}")
|
|
# pop child entry to indicate we no longer managing this subactor
|
|
subactor, proc, portal = actor_nursery._children.pop(subactor.uid)
|
|
|
|
# cancel result waiter that may have been spawned in
|
|
# tandem if not done already
|
|
if cancel_scope:
|
|
log.warning(
|
|
"Cancelling existing result waiter task for "
|
|
f"{subactor.uid}")
|
|
cancel_scope.cancel()
|
|
else:
|
|
# `multiprocessing`
|
|
# async with trio.open_nursery() as nursery:
|
|
await mp_new_proc(
|
|
name=name,
|
|
actor_nursery=actor_nursery,
|
|
subactor=subactor,
|
|
errors=errors,
|
|
# passed through to actor main
|
|
bind_addr=bind_addr,
|
|
parent_addr=parent_addr,
|
|
_runtime_vars=_runtime_vars,
|
|
task_status=task_status,
|
|
)
|
|
|
|
|
|
async def mp_new_proc(
|
|
|
|
name: str,
|
|
actor_nursery: 'ActorNursery', # type: ignore # noqa
|
|
subactor: Actor,
|
|
errors: Dict[Tuple[str, str], Exception],
|
|
# passed through to actor main
|
|
bind_addr: Tuple[str, int],
|
|
parent_addr: Tuple[str, int],
|
|
_runtime_vars: Dict[str, Any], # serialized and sent to _child
|
|
*,
|
|
task_status: TaskStatus[Portal] = trio.TASK_STATUS_IGNORED
|
|
|
|
) -> None:
|
|
async with trio.open_nursery() as nursery:
|
|
assert _ctx
|
|
start_method = _ctx.get_start_method()
|
|
if start_method == 'forkserver':
|
|
# XXX do our hackery on the stdlib to avoid multiple
|
|
# forkservers (one at each subproc layer).
|
|
fs = forkserver._forkserver
|
|
curr_actor = current_actor()
|
|
if is_main_process() and not curr_actor._forkserver_info:
|
|
# if we're the "main" process start the forkserver
|
|
# only once and pass its ipc info to downstream
|
|
# children
|
|
# forkserver.set_forkserver_preload(enable_modules)
|
|
forkserver.ensure_running()
|
|
fs_info = (
|
|
fs._forkserver_address,
|
|
fs._forkserver_alive_fd,
|
|
getattr(fs, '_forkserver_pid', None),
|
|
getattr(
|
|
resource_tracker._resource_tracker, '_pid', None),
|
|
resource_tracker._resource_tracker._fd,
|
|
)
|
|
else:
|
|
assert curr_actor._forkserver_info
|
|
fs_info = (
|
|
fs._forkserver_address,
|
|
fs._forkserver_alive_fd,
|
|
fs._forkserver_pid,
|
|
resource_tracker._resource_tracker._pid,
|
|
resource_tracker._resource_tracker._fd,
|
|
) = curr_actor._forkserver_info
|
|
else:
|
|
fs_info = (None, None, None, None, None)
|
|
|
|
proc: mp.Process = _ctx.Process( # type: ignore
|
|
target=_mp_main,
|
|
args=(
|
|
subactor,
|
|
bind_addr,
|
|
fs_info,
|
|
start_method,
|
|
parent_addr,
|
|
),
|
|
# daemon=True,
|
|
name=name,
|
|
)
|
|
# `multiprocessing` only (since no async interface):
|
|
# register the process before start in case we get a cancel
|
|
# request before the actor has fully spawned - then we can wait
|
|
# for it to fully come up before sending a cancel request
|
|
actor_nursery._children[subactor.uid] = (subactor, proc, None)
|
|
|
|
proc.start()
|
|
if not proc.is_alive():
|
|
raise ActorFailure("Couldn't start sub-actor?")
|
|
|
|
log.runtime(f"Started {proc}")
|
|
|
|
try:
|
|
# wait for actor to spawn and connect back to us
|
|
# channel should have handshake completed by the
|
|
# local actor by the time we get a ref to it
|
|
event, chan = await actor_nursery._actor.wait_for_peer(
|
|
subactor.uid)
|
|
portal = Portal(chan)
|
|
actor_nursery._children[subactor.uid] = (subactor, proc, portal)
|
|
|
|
# unblock parent task
|
|
task_status.started(portal)
|
|
|
|
# wait for ``ActorNursery`` block to signal that
|
|
# subprocesses can be waited upon.
|
|
# This is required to ensure synchronization
|
|
# with user code that may want to manually await results
|
|
# from nursery spawned sub-actors. We don't want the
|
|
# containing nurseries here to collect results or error
|
|
# while user code is still doing it's thing. Only after the
|
|
# nursery block closes do we allow subactor results to be
|
|
# awaited and reported upwards to the supervisor.
|
|
await actor_nursery._join_procs.wait()
|
|
|
|
finally:
|
|
# XXX: in the case we were cancelled before the sub-proc
|
|
# registered itself back we must be sure to try and clean
|
|
# any process we may have started.
|
|
|
|
reaping_cancelled: bool = False
|
|
cancel_scope: Optional[trio.CancelScope] = None
|
|
cancel_exc: Optional[trio.Cancelled] = None
|
|
|
|
if portal in actor_nursery._cancel_after_result_on_exit:
|
|
try:
|
|
# async with trio.open_nursery() as n:
|
|
# n.cancel_scope.shield = True
|
|
cancel_scope = await nursery.start(
|
|
cancel_on_completion,
|
|
portal,
|
|
subactor,
|
|
errors
|
|
)
|
|
except trio.Cancelled as err:
|
|
cancel_exc = err
|
|
|
|
# if the reaping task was cancelled we may have hit
|
|
# a race where the subproc disconnected before we
|
|
# could send it a message to cancel (classic 2 generals)
|
|
# in that case, wait shortly then kill the process.
|
|
reaping_cancelled = True
|
|
|
|
if proc.is_alive():
|
|
with trio.move_on_after(0.1) as cs:
|
|
cs.shield = True
|
|
await proc_waiter(proc)
|
|
|
|
if cs.cancelled_caught:
|
|
proc.terminate()
|
|
|
|
if not reaping_cancelled and proc.is_alive():
|
|
await proc_waiter(proc)
|
|
|
|
# TODO: timeout block here?
|
|
proc.join()
|
|
|
|
log.debug(f"Joined {proc}")
|
|
# pop child entry to indicate we are no longer managing subactor
|
|
subactor, proc, portal = actor_nursery._children.pop(subactor.uid)
|
|
|
|
# cancel result waiter that may have been spawned in
|
|
# tandem if not done already
|
|
if cancel_scope:
|
|
log.warning(
|
|
"Cancelling existing result waiter task for "
|
|
f"{subactor.uid}")
|
|
cancel_scope.cancel()
|
|
|
|
elif reaping_cancelled: # let the cancellation bubble up
|
|
assert cancel_exc
|
|
raise cancel_exc
|