[release/8.0] Ensure Parallel.ForAsync unregisters from CancellationToken #93674
+4
−1
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Backport of #93672 to release/8.0
/cc @stephentoub
Customer Impact
An infinite memory leak as long as the developer is reusing the same CancellationTokenSource. If they drop the CTS, then all the state it was keeping alive also goes away.
Testing
All existing tests continue to pass. It’s challenging to write a unit test for this specific functionality and fix, as the storage for this information isn’t observable via public surface area. However, it was validated using a derivation of the original supplied repo. Before the fix, memory usage keeps going up and up; after the fix, it remains steady.
Risk
Minimal risk, this only adds a call to Dispose at the right location.
IMPORTANT: If this backport is for a servicing release, please verify that:
The PR target branch is
release/X.0-staging
, notrelease/X.0
.If the change touches code that ships in a NuGet package, you have added the necessary package authoring and gotten it explicitly reviewed.