[issue27585] asyncio.Lock deadlock after cancellation

Changes by Yury Selivanov : -- resolution: -> fixed stage: -> resolved status: open -> closed versions: +Python 3.5, Python 3.7 ___ Python tracker

[issue27585] asyncio.Lock deadlock after cancellation

Changes by Guido van Rossum : -- nosy: -gvanrossum ___ Python tracker ___ ___

[issue27585] asyncio.Lock deadlock after cancellation

Changes by Yury Selivanov : -- pull_requests: +2103 ___ Python tracker ___ ___

[issue27585] asyncio.Lock deadlock after cancellation

Changes by Yury Selivanov : -- pull_requests: +2102 ___ Python tracker ___ ___

[issue27585] asyncio.Lock deadlock after cancellation

Yury Selivanov added the comment: New changeset 7be651c7aad8e4d46012205811b58ef127b08e0e by Yury Selivanov in branch 'master': bpo-27585: Add a NEWS entry for #1031 (#2036) https://github.com/python/cpython/commit/7be651c7aad8e4d46012205811b58ef127b08e0e --

[issue27585] asyncio.Lock deadlock after cancellation

Changes by Yury Selivanov : -- pull_requests: +2101 ___ Python tracker ___ ___

[issue27585] asyncio.Lock deadlock after cancellation

Guido van Rossum added the comment: I'm really sorry, but I personally don't have time to look into this. If you have a fix in mind you can send a PR to GitHub mentioning bpi-27585. -- ___ Python tracker

[issue27585] asyncio.Lock deadlock after cancellation

Alexey Popravka added the comment: Also there is the same problem with asyncio.Condition wait() / notify() couple as it repeats the same Lock.acquire()/release() logic -- ___ Python tracker

[issue27585] asyncio.Lock deadlock after cancellation

Alexey Popravka added the comment: Hi guys! Any update on this? I've just hit this issue. Cancelled futures in _waiters is not a problem (any more). There is still a problem when release() wakes up next waiter but task waiting for it gets cancelled and so all the rest waiters are in pending

[issue27585] asyncio.Lock deadlock after cancellation

Changes by Mathieu Sornay : -- pull_requests: +1188 ___ Python tracker ___ ___

[issue27585] asyncio.Lock deadlock after cancellation

Mathieu Sornay added the comment: Fix attempt : https://github.com/python/asyncio/pull/467 -- ___ Python tracker ___

[issue27585] asyncio.Lock deadlock after cancellation

Guido van Rossum added the comment: Looks like create_waiter() entered the with-statement but didn't leave it properly due to the cancellation, right? @1st1 any idea? async with bug or asyncio bug? -- ___ Python tracker

[issue27585] asyncio.Lock deadlock after cancellation

Mathieu Sornay added the comment: I might have found another pathological case not fixed by https://github.com/python/asyncio/pull/393 Tested in 3.6.0b3 The deadlock.py file prints : DEADLOCK HERE _locked: False _waiters: deque([]) -- nosy: +msornay versions: +Python 3.6 -Python

[issue27585] asyncio.Lock deadlock after cancellation

Guido van Rossum added the comment: OK, merged upstream. It'll eventually come down to Python 3.5.3 and 3.6. On Thu, Aug 4, 2016 at 1:28 PM, sss wrote: > > sss added the comment: > > Thank you. This looks good to me > > -- > >

[issue27585] asyncio.Lock deadlock after cancellation

sss added the comment: Thank you. This looks good to me -- ___ Python tracker ___ ___ Python-bugs-list

[issue27585] asyncio.Lock deadlock after cancellation

Guido van Rossum added the comment: Tentative fix is in https://github.com/python/asyncio/pull/393 -- ___ Python tracker ___

[issue27585] asyncio.Lock deadlock after cancellation

sss added the comment: Yes I'm running python-3.5.2. -- ___ Python tracker ___ ___ Python-bugs-list mailing

[issue27585] asyncio.Lock deadlock after cancellation

Guido van Rossum added the comment: Does this repro with the latest Python 3.5.2? IIRC the lock code was overhauled after 3.5.0 or 3.5.1. (PS. These are tasks, not threads.) --Guido (mobile) On Aug 4, 2016 2:33 AM, "sss" wrote: sss added the comment: Yes, await

[issue27585] asyncio.Lock deadlock after cancellation

sss added the comment: Yes, await asyncio.sleep(0) does fix it, but it would be weird if I'm supposed to put those all over my code. I made a new reproducer now that uses 2 threads in case it's not allowed to take the same lock twice from the same thread. -- Added file:

[issue27585] asyncio.Lock deadlock after cancellation

R. David Murray added the comment: If you give the loop a chance to run (an await asyncio.sleep(0)) before doing the acquire) it does not deadlock. I don't understand enough of the asyncio internals to know if this is expected or a bug. -- nosy: +r.david.murray

[issue27585] asyncio.Lock deadlock after cancellation

New submission from sss: The lock.py file prints DEADLOCK HERE _locked: False _waiters: deque([]) I think the problem is that acquire() will block because of the cancelled future in _waiters, but release() has already ran so no one will wake it up. -- components: asyncio files: