| msg270944 - (view) |
Author: (sss) |
Date: 2016-07-21 17:06 |
| 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. |
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| msg270947 - (view) |
Author: R. David Murray (r.david.murray) *  |
Date: 2016-07-21 17:26 |
| 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. |
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| msg271962 - (view) |
Author: (sss) |
Date: 2016-08-04 09:33 |
| 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. |
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| msg271986 - (view) |
Author: Guido van Rossum (gvanrossum) * |
Date: 2016-08-04 15:06 |
| 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" <report@bugs.python.org> wrote: 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: http://bugs.python.org/file44007/lock2.py _______________________________________ Python tracker <report@bugs.python.org> <http://bugs.python.org/issue27585> _______________________________________ |
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| msg271987 - (view) |
Author: (sss) |
Date: 2016-08-04 15:09 |
| Yes I'm running python-3.5.2. |
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| msg271990 - (view) |
Author: Guido van Rossum (gvanrossum) * |
Date: 2016-08-04 16:13 |
| Tentative fix is in https://github.com/python/asyncio/pull/393 |
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| msg271999 - (view) |
Author: (sss) |
Date: 2016-08-04 20:28 |
| Thank you. This looks good to me |
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| msg272042 - (view) |
Author: Guido van Rossum (gvanrossum) * |
Date: 2016-08-05 16:55 |
| 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 <report@bugs.python.org> wrote: > > sss added the comment: > > Thank you. This looks good to me > > ---------- > > _______________________________________ > Python tracker <report@bugs.python.org> > <http://bugs.python.org/issue27585> > _______________________________________ |
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| msg280873 - (view) |
Author: Mathieu Sornay (msornay) * |
Date: 2016-11-15 18:26 |
| 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([]) |
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| msg280874 - (view) |
Author: Guido van Rossum (gvanrossum) * |
Date: 2016-11-15 18:53 |
| 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? |
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| msg280938 - (view) |
Author: Mathieu Sornay (msornay) * |
Date: 2016-11-16 12:08 |
| Fix attempt : https://github.com/python/asyncio/pull/467 |
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| msg293922 - (view) |
Author: Alexey Popravka (Alexey Popravka) |
Date: 2017-05-18 12:47 |
| 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 state forever. I've attach one more test to reproduce this issue. |
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| msg293925 - (view) |
Author: Alexey Popravka (Alexey Popravka) |
Date: 2017-05-18 15:03 |
| Also there is the same problem with asyncio.Condition wait() / notify() couple as it repeats the same Lock.acquire()/release() logic |
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| msg293929 - (view) |
Author: Guido van Rossum (gvanrossum) * |
Date: 2017-05-18 17:14 |
| 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. |
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| msg295568 - (view) |
Author: Yury Selivanov (yselivanov) * |
Date: 2017-06-09 20:34 |
| 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 |
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