fix: add read lock to WAL segment Flush to prevent data race with Close#893
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mattisonchao merged 1 commit intomainfrom Feb 23, 2026
Merged
fix: add read lock to WAL segment Flush to prevent data race with Close#893mattisonchao merged 1 commit intomainfrom
mattisonchao merged 1 commit intomainfrom
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The runSync goroutine calls segment.Flush() without holding any lock, while Close() concurrently calls Unmap() under the write lock. This adds RLock/RUnlock to Flush() so the two operations are properly serialized, and guards against a nil txnMappedFile after Unmap. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Motivation
TestCoordinatorE2Eis flaky due to a data race between the WALrunSyncgoroutine callingsegment.Flush()(which reads the mmap) andwal.Close()callingsegment.Close()→MMap.Unmap()(which writes/invalidates the mmap). The race was latent in the WAL code and surfaced after the follower controller lifecycle refactor in #887 changed shutdown timing.CI failure: https://github.com/oxia-db/oxia/actions/runs/22312993235/job/64549930899
Modification
RLock/RUnlocktoreadWriteSegment.Flush()to synchronize against the write lock already held byClose(). This ensures eitherFlush()completes beforeUnmap()begins, orUnmap()completes first andFlush()seestxnMappedFile == niland returns safely.