[3.11] gh-90155: Fix bug in asyncio.Semaphore and strengthen FIFO guarantee (GH-93222) #97019
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…antee (pythonGH-93222) The main problem was that an unluckily timed task cancellation could cause the semaphore to be stuck. There were also doubts about strict FIFO ordering of tasks allowed to pass. The Semaphore implementation was rewritten to be more similar to Lock. Many tests for edge cases (including cancellation) were added. (cherry picked from commit 24e0379) Co-authored-by: Cyker Way <[email protected]>
gvanrossum
approved these changes
Sep 22, 2022
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@pablogsal I'm not sure whether this ought to go into 3.11.0 or 3.11.1. The cancel-related bug was introduced in March 2022 and backported all the way to 3.9. But it's a lot of code to disturb a release candidate with.
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The main problem was that an unluckily timed task cancellation could cause
the semaphore to be stuck. There were also doubts about strict FIFO ordering
of tasks allowed to pass.
The Semaphore implementation was rewritten to be more similar to Lock.
Many tests for edge cases (including cancellation) were added.
(cherry picked from commit 24e0379)
Co-authored-by: Cyker Way [email protected]