Fix race between async insert completion and query_log entry#96958
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alexey-milovidov merged 3 commits intomasterfrom Feb 16, 2026
Merged
Fix race between async insert completion and query_log entry#96958alexey-milovidov merged 3 commits intomasterfrom
alexey-milovidov merged 3 commits intomasterfrom
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In `AsynchronousInsertQueue::processData`, the `finish_entries` lambda was calling `entry->finish()` (which sets the promise and wakes up the client waiting with `wait_for_async_insert=1`) before `logQueryFinish` (which writes the `QueryFinish` entry to `query_log`). This created a race window: the client could wake up, execute `SYSTEM FLUSH LOGS`, and query `system.query_log` before the `QueryFinish` entry was even added to the log buffer. Under TSan or CPU contention, this window was wide enough to trigger reliably. Fix by reordering: write log entries first, then notify the waiting clients. This is consistent with the error path, where `logQueryException` already runs before `finishWithException`. Note: this is complementary to #96957, which addresses a similar race in the HTTP/curl path at the test level. That PR does not cover this case because test `02790` uses the native client, not curl, and the race window is in `AsynchronousInsertQueue`, not in the HTTP response path. Closes #80813 Co-Authored-By: Claude Opus 4.6 <[email protected]>
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Summary
AsynchronousInsertQueue::processDatawhereentry->finish()(which wakes up the client) was called beforelogQueryFinish(which writes theQueryFinishentry toquery_log)wait_for_async_insert=1could wake up and executeSYSTEM FLUSH LOGS+SELECT FROM system.query_logbefore theQueryFinishentry was added to the log bufferlogQueryExceptionalready runs beforefinishWithExceptionRelation to #96957: that PR addresses a similar race in the HTTP/curl path at the test level (retry loops). It does not cover this case because test
02790uses the native client (not curl), and the race window is inAsynchronousInsertQueue, not in the HTTP response path. The two fixes are complementary.Test plan
02790_async_queries_in_query_logpasses consistently (5/5 local runs)Closes #80813
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