Bring back the reader-writer lock for RcwCache - #120675
#120675Merged
jkoritzinsky merged 2 commits intoOct 14, 2025
dotnet:maindotnet/runtime:mainfrom
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Bring back the reader-writer lock for RcwCache#120675jkoritzinsky merged 2 commits intodotnet:maindotnet/runtime:mainfrom jkoritzinsky:rcwcache-rwlock-try2jkoritzinsky/runtime:rcwcache-rwlock-try2Copy head branch name to clipboard
jkoritzinsky merged 2 commits into
dotnet:maindotnet/runtime:mainfrom
jkoritzinsky:rcwcache-rwlock-try2jkoritzinsky/runtime:rcwcache-rwlock-try2Copy head branch name to clipboard
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Instead of writing to `_cache` while under a reader lock, delay the cleanup until we can acquire a writer lock. We do this instead of doing an upgradeable lock as `ReaderWriterLockSlim` only supports one upgradeable reader thread at a time, removing the benefit of having an rwlock in the first place.
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Pull Request Overview
This PR reverts a previous change that replaced a ReaderWriterLockSlim with a simple Lock in the RcwCache class, restoring the reader-writer lock mechanism for better concurrency. The change improves the cache's ability to handle concurrent read operations while ensuring thread-safe cleanup of dead entries.
Key changes:
- Replaces the simple
LockwithReaderWriterLockSlimfor the RcwCache - Implements a two-phase locking strategy in
FindProxyForComInstanceto avoid upgradeable locks - Updates all cache operations to use appropriate read/write locks with proper try-finally blocks
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AaronRobinsonMSFT
approved these changes
Oct 13, 2025
…pServices/ComWrappers.cs Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
AaronRobinsonMSFT
approved these changes
Oct 13, 2025
jkoritzinsky
enabled auto-merge (squash)
October 13, 2025 21:40
This was referenced Oct 14, 2025
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Instead of writing to
_cachewhile under a reader lock, delay the cleanup until we can acquire a writer lock.We do this instead of doing an upgradeable lock as
ReaderWriterLockSlimonly supports one upgradeable reader thread at a time, removing the benefit of having an rwlock in the first place.This matches the logic in the .NET 9 CoreCLR implementation of ComWrappers.
Reverts #120370
Fixes #120470