Fix a couple of issues with StackTraceSymbols.TryGetReader #67300
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The implementation has a comment about how ConditionalWeakTable prevents multiple threads from racing to create readers, but CWT doesn't invole the delegate under its lock. So multiple threads can actually race to create a reader, and if one loses, it won't Dispose the reader it created. On top of this, every call to TryGetReader is allocating a closure, even if one of the fast paths is hit, because the cache callback captures all the parameters.
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I couldn't figure out the best area label to add to this PR. If you have write-permissions please help me learn by adding exactly one area label. |
ghost
assigned
stephentoub
commented
Mar 29, 2022
...libraries/System.Private.CoreLib/src/System/Runtime/CompilerServices/ConditionalWeakTable.cs
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jkotas
approved these changes
Mar 29, 2022
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Failure is #60962 |
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The implementation has a comment about how ConditionalWeakTable prevents multiple threads from racing to create readers, but CWT doesn't invole the delegate under its lock. So multiple threads can actually race to create a reader, and if one loses, it won't Dispose the reader it created. On top of this, every call to TryGetReader is allocating a closure, even if one of the fast paths is hit, because the cache callback captures all the parameters.