Avoid deadlock on channel mutex when stopping pool #148
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Let the message_manager_loop run at least until the PoolManager is fully stopped, to avoid the workers from hanging on writing to an (overflown) pipe while holding the channel mutex, which would result in a deadlock - causing a delay of 60 seconds, the BrokenProcessPool exception and an unclean shutdown of workers.
emaxx-google
commented
Dec 20, 2024
| f.cancel() | ||
| time.sleep(EPS * CNT / 2) | ||
| pool.stop() | ||
| pool.join() |
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I haven't found a good way to assert the state here: neither that there was no BrokenProcessPool in pool_manager_loop() nor that we slept for LOCK_TIMEOUT:
- For the former, I tried changing the
PoolContext.statussetter to allow transitioning fromSTOPPEDtoERROR, but apparently there are other places that try to setERROReven in "good" shutdown scenarios. - For the latter, it seems brittle to rely on clocks in the tests. Unless maybe we override
LOCK_TIMEOUTto some really big number in this test?..
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Let the message_manager_loop run at least until the PoolManager is fully stopped, to avoid the workers from hanging on writing to an (overflown) pipe while holding the channel mutex, which would result in a deadlock - causing a delay of 60 seconds, the BrokenProcessPool exception and an unclean shutdown of workers.
This fixes #147.