Fix flaky tests: curl + SYSTEM FLUSH LOGS race condition#96957
Merged
alexey-milovidov merged 4 commits intomasterfrom Feb 15, 2026
Merged
Fix flaky tests: curl + SYSTEM FLUSH LOGS race condition#96957alexey-milovidov merged 4 commits intomasterfrom
alexey-milovidov merged 4 commits intomasterfrom
Conversation
The test sends inserts via HTTP (curl) and then immediately queries `system.query_log`. There is a race between the HTTP response being sent back to curl and the `query_log` entry being written — under TSan this race window is wide enough for the last RowBinary insert's log entry to be missing when `SYSTEM FLUSH LOGS` runs. Fix by retrying `SYSTEM FLUSH LOGS` in a loop until all 6 expected insert entries appear in `query_log`. #84364 Co-Authored-By: Claude Opus 4.6 <[email protected]>
Contributor
Apply the same fix as for `02423_insert_stats_behaviour`: when tests send requests via HTTP (curl) and then query `system.query_log` or other system log tables, there is a race between the HTTP response being sent and the log entry being written. Under TSan this race window is wide enough to cause flaky failures. Fix all affected tests by retrying `SYSTEM FLUSH LOGS` in a loop until the expected entries appear. Co-Authored-By: Claude Opus 4.6 <[email protected]>
Same fix for `01526_initial_query_id`, `02246_is_secure_query_log`, and `02908_many_requests_to_system_replicas`. Co-Authored-By: Claude Opus 4.6 <[email protected]>
Add a check to `various_checks.sh` that detects shell tests using curl/HTTP to send requests and then calling `SYSTEM FLUSH LOGS` without a retry loop. This pattern is racy because the `query_log` entry is written after the HTTP response is sent (see the comment in `executeQuery.cpp:2324`), so the entry may not exist when `FLUSH LOGS` runs. The check finds .sh test files that use curl + system log tables + FLUSH LOGS but don't have a retry loop (for/while + sleep/break), and reports them as style violations. Co-Authored-By: Claude Opus 4.6 <[email protected]>
alexey-milovidov
changed the title
02423_insert_stats_behaviour
alexey-milovidov
added a commit
that referenced
this pull request
Feb 15, 2026
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]>
3 tasks
Member
Author
|
This is a great observation! |
robot-ch-test-poll
added
the
pr-synced-to-cloud
1 task
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fix flaky tests caused by a race between HTTP response being sent and the
query_logentry being written. The code inexecuteQuery.cpp:2324explicitly documents thatquery_finish_callback()(which sends the HTTP response) runs beforeonFinish()(which writes the QueryFinish log entry). Under TSan this race window is wide enough for the last entry to be missing.Fix 17 affected tests by retrying
SYSTEM FLUSH LOGSin a loop until all expected entries appear. Add a style check tovarious_checks.shthat prevents this anti-pattern from reappearing.Tests fixed:
02423_insert_stats_behaviour,01194_http_query_id,01526_initial_query_id,01526_max_untracked_memory,01661_referer,02156_async_insert_query_log,02246_is_secure_query_log,02456_async_inserts_logs,02494_query_cache_http_introspection,02570_fallback_from_async_insert,02714_async_inserts_empty_data,02725_async_insert_table_setting,02841_parallel_replicas_summary,02908_many_requests_to_system_replicas,03237_insert_sparse_columns_mem,03338_http_compression_profile_events,03723_max_insert_block_size_bytes_httpCloses #84364
Changelog category (leave one):
Changelog entry (a user-readable short description of the changes that goes into CHANGELOG.md):
...
Documentation entry for user-facing changes