Avoid deadlock when two tasks are concurrently waiting for an unresolved ActorFuture
#5709
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Can one of the admins verify this patch? |
graingert
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Jan 26, 2022
graingert
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Jan 26, 2022
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Jan 26, 2022
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ian-r-rose
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Jan 28, 2022
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Thanks @graingert, this is a nice piece of work, and the implementation seems sound to me. A few design questions, but nothing major.
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gjoseph92
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Not too important, but I could see some type annotations here being helpful, mostly just for future readers. Particularly for things like:
-
ActorFuture.resultreturn type (makingActorFuturegeneric would be necessary) -
ActorFuture.__await__return type -
_ActorFuture._out
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Hmm, tried your PR with Python 3.10.1 and the results were not completely conclusive: Complete build log with all packages used and step taken to run the test suite. |
ian-r-rose
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Feb 9, 2022
| await self._event.wait() | ||
| out = self._out | ||
| assert out is not None | ||
| return out.unwrap() |
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Can you elucidate a bit more the purpose of these wrapper classes, as opposed to the more direct inspection of the result that there was previously? It seems like they are related to trying to get a chain of custody for the generic _T, but I'm not sure it really buys much since the setting of the result here isn't checked, so we ultimately have an _OK(Unknown).
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Yeah ideally this would have been done with TypedDict but they're not supported python/mypy#3863
class _OK(TypedDict, Generic[_T]):
status: Literal["OK"]
result: _T
class _Error(TypedDict):
status: Literal["error"]
exception: Exception
...
def _set_result(self, out: _Error | _OK[_T]): ...It seems like they are related to trying to get a chain of custody for the generic _T, but I'm not sure it really buys much since the setting of the result here isn't checked, so we ultimately have an _OK(Unknown).
I needed to draw the line somewhere of what's typed and what's not in this PR, and chose to type all the methods and classes of BaseActorFuture. _Error | _OK[_T] | None is also needed for the internal state ActorFuture so I think it's worth it for now
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I love the new generic machinery @graingert, and I like that it brings it a bit closer to how |
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fjetter
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this keeps the somewhat odd late asyncio.Event() construction in one location that can be removed by pyupgrade
each test uses a different method so it's confusing me to edit both ends of the test file
…rActorFuture->EagerActorFuture
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fjetter
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Feb 17, 2022
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Waiting for builds to pass and then will merge. |
jrbourbeau
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ActorFuture
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All green 🥲 |
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Was this supposed to be python310-fix? Because it doesn’t work for me: test_client.py::test_client_gather_semaphore_loop, |
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Thank you @graingert ! This looks great. Sorry for us taking so long with reviewing it. |
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