maytasm opened a new pull request, #17823: URL: https://github.com/apache/druid/pull/17823
Fix resource leak for GroupBy query merge buffer when match result cache ### Description In processing/src/main/java/org/apache/druid/query/groupby/GroupByQueryQueryToolChest#initAndMergeGroupByResults, we acquire the resource via groupByResourcesReservationPool.reserve() and then we add a Closer to the Sequences which runs after execution of the query (after the mergedSequence accumulate/toYielder). However, in ResultLevelCachingQueryRunner, if useResultCache is enabled and we return cached result, then this will cause resource to leak. Resource (mergeBuffer) will be acquired in https://github.com/apache/druid/blob/master/server/src/main/java/org/apache/druid/query/ResultLevelCachingQueryRunner.java#L101 but in https://github.com/apache/druid/blob/master/server/src/main/java/org/apache/druid/query/ResultLevelCachingQueryRunner.java#L109 the cached result set is returned instead of resultFromClient. The mergedSequence will not be accumulate and the closer will not be run. Hence, mergeBuffer will not be release back to the pool This fix is to only acquired the resource if we have a result cache miss by moving https://github.com/apache/druid/blob/master/server/src/main/java/org/apache/druid/query/ResultLevelCachingQueryRunner.java#L101 to the else condition (result cache miss) This PR has: - [x] been self-reviewed. - [ ] using the [concurrency checklist](https://github.com/apache/druid/blob/master/dev/code-review/concurrency.md) (Remove this item if the PR doesn't have any relation to concurrency.) - [ ] added documentation for new or modified features or behaviors. - [ ] a release note entry in the PR description. - [ ] added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links. - [ ] added or updated version, license, or notice information in [licenses.yaml](https://github.com/apache/druid/blob/master/dev/license.md) - [ ] added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader. - [ ] added unit tests or modified existing tests to cover new code paths, ensuring the threshold for [code coverage](https://github.com/apache/druid/blob/master/dev/code-review/code-coverage.md) is met. - [ ] added integration tests. - [ ] been tested in a test Druid cluster. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
