condition lock not re-acquired

[christof]

BPO	33638
Nosy	@asvetlov, @1st1, @miss-islington
PRs	bpo-32751: Wait for task cancellation in asyncio.wait_for() #7216 [3.7] bpo-32751: Wait for task cancellation in asyncio.wait_for() (GH-7216) #7223
Superseder	bpo-32751: wait_for(future, ...) should wait for the future (even if a timeout occurs)

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = None
closed_at = <Date 2018-05-30.01:01:18.215>
created_at = <Date 2018-05-24.19:10:23.885>
labels = ['type-bug', 'expert-asyncio']
title = 'condition lock not re-acquired'
updated_at = <Date 2018-05-30.01:01:18.214>
user = 'https://bugs.python.org/christof'

bugs.python.org fields:

activity = <Date 2018-05-30.01:01:18.214>
actor = 'yselivanov'
assignee = 'none'
closed = True
closed_date = <Date 2018-05-30.01:01:18.215>
closer = 'yselivanov'
components = ['asyncio']
creation = <Date 2018-05-24.19:10:23.885>
creator = 'christof'
dependencies = []
files = []
hgrepos = []
issue_num = 33638
keywords = ['patch']
message_count = 5.0
messages = ['317604', '317608', '318063', '318096', '318131']
nosy_count = 4.0
nosy_names = ['asvetlov', 'yselivanov', 'miss-islington', 'christof']
pr_nums = ['7216', '7223']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = '32751'
type = 'behavior'
url = 'https://bugs.python.org/issue33638'
versions = ['Python 3.6']

[christof]

Hello,

I have a simple code which triggers a timeout if a task did not complete

import asyncio

async def task_timeout():
    condition = asyncio.Condition()
    with await condition:
        try:
            await asyncio.wait_for(condition.wait(), timeout=4)
        except asyncio.TimeoutError as e:
 
            print("timeout reached")
            # uncomment this line to make the code work
            # await asyncio.sleep(0)


f = asyncio.ensure_future(task_timeout())

loop= asyncio.get_event_loop()
loop.run_until_complete(f)

It throws an exception when leaving the scope for the condition because it expects the lock to be acquired:

RuntimeError: Lock is not acquired.

If you uncomment the line to sleep, it will work because it will continue in the coroutine Condition.wait and call:
yield from self.acquire() => locks.py line 355

I think this is a bug and that this behaviour is not the expected one.

[christof]

In my previous comment, what I want to implement is not a timeout for a task to complete but more precisely a timeout triggered if the coroutine was not wake up by a notify on the condition.

[1st1]

This is caused by wait_for not waiting for the cancelled task. https://bugs.python.org/issue32751 tracks that bug.

[1st1]

New changeset e2b340a by Yury Selivanov (Elvis Pranskevichus) in branch 'master':
bpo-32751: Wait for task cancellation in asyncio.wait_for() (GH-7216)
e2b340a

[miss-islington]

New changeset d8948c5 by Miss Islington (bot) in branch '3.7':
bpo-32751: Wait for task cancellation in asyncio.wait_for() (GH-7216)
d8948c5