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🟢 Approval recommended
The synchronization issue is addressed consistently in both reviewed files, with no unresolved blocking issues.
0 open findings
What changed in this PR
This PR fixes a data race in concurrent access to object and resource pool free chunks.
Changes:
- Removes unlocked
_free_chunks.empty()checks. - Protects all free-chunk access with the existing mutex.
🧠 Review effort: Lite
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wwbmmm
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[replied by brpc-oncall robot] Removing the unlocked read fixes the data race, but it also deletes a deliberate fast path that avoided the global mutex in the high-contention case; please keep a race-free fast path (atomic free-chunk count) or show the cost is acceptable.
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What problem does this PR solve?
Issue Number: resolve
Problem Summary:
ObjectPoolandResourcePoolaccess_free_chunksfrom multiple threads.pop_free_chunk()previously read_free_chunks.empty()before acquiring_free_chunks_mutex, whilepush_free_chunk()modifies the same vector underthe mutex. Concurrent reads and writes of
std::vectormetadata are a C++ datarace.
What is changed and the side effects?
Changed:
_nfree_chunks, a relaxed atomic count of global free chunks, to bothObjectPoolandResourcePool._free_chunks_mutexafter every successful push andpop.
pop_free_chunk()._free_chunks.empty()check after acquiring themutex.
cross-thread reuse.
Side effects:
Performance effects:
The empty-list fast path no longer reads
std::vectorwithoutsynchronization. A relaxed atomic load avoids mutex acquisition when no
global free chunk is available, preserving the intended hot-path behavior.
Breaking backward compatibility:
None.