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Harden `trio` spawner process waiting 

Always shield waiting for he process and always run
``trio.Process.__aexit__()`` on teardown. This enforces
that shutdown happens to due cancellation triggered inside
the sub-actor instead of the process being killed externally
by the parent.
dereg_on_channel_aclose
Tyler Goodlet 2020-08-08 14:43:25 -04:00
parent fe45d99f65
commit 532429aec9
1 changed files with 21 additions and 11 deletions
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32
tractor/_spawn.py
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@ -148,7 +148,7 @@ async def cancel_on_completion(
else: else:
log.info( log.info(
f"Cancelling {portal.channel.uid} gracefully " f"Cancelling {portal.channel.uid} gracefully "
"after result {result}") f"after result {result}")
# cancel the process now that we have a final result # cancel the process now that we have a final result
await portal.cancel_actor() await portal.cancel_actor()
@ -159,7 +159,6 @@ async def spawn_subactor(
subactor: 'Actor', subactor: 'Actor',
parent_addr: Tuple[str, int], parent_addr: Tuple[str, int],
): ):
spawn_cmd = [ spawn_cmd = [
sys.executable, sys.executable,
"-m", "-m",
@ -184,13 +183,19 @@ async def spawn_subactor(
] ]
proc = await trio.open_process(spawn_cmd) proc = await trio.open_process(spawn_cmd)
yield proc try:
yield proc
finally:
# XXX: do this **after** cancellation/tearfown
# to avoid killing the process too early
# since trio does this internally on ``__aexit__()``
# XXX: do this **after** cancellation/tearfown # NOTE: we always "shield" join sub procs in
# to avoid killing the process too early # the outer scope since no actor zombies are
# since trio does this internally on ``__aexit__()`` # ever allowed. This ``__aexit__()`` also shields
async with proc: # internally.
log.debug(f"Terminating {proc}") async with proc:
log.debug(f"Terminating {proc}")
async def new_proc( async def new_proc(
@ -243,16 +248,21 @@ async def new_proc(
task_status.started(portal) task_status.started(portal)
# wait for ActorNursery.wait() to be called # wait for ActorNursery.wait() to be called
await actor_nursery._join_procs.wait() with trio.CancelScope(shield=True):
await actor_nursery._join_procs.wait()
if portal in actor_nursery._cancel_after_result_on_exit: if portal in actor_nursery._cancel_after_result_on_exit:
cancel_scope = await nursery.start( cancel_scope = await nursery.start(
cancel_on_completion, portal, subactor, errors) cancel_on_completion, portal, subactor, errors)
# Wait for proc termination but **dont'** yet call # Wait for proc termination but **dont' yet** call
# ``trio.Process.__aexit__()`` (it tears down stdio # ``trio.Process.__aexit__()`` (it tears down stdio
# which will kill any waiting remote pdb trace). # which will kill any waiting remote pdb trace).
await proc.wait()
# always "hard" join sub procs:
# no actor zombies allowed
with trio.CancelScope(shield=True):
await proc.wait()
else: else:
# `multiprocessing` # `multiprocessing`
assert _ctx assert _ctx