warren288 opened a new issue #7465: SQLMetadataSegmentManager may trigger a thread safe problem when disabling all segments at once URL: https://github.com/apache/incubator-druid/issues/7465 Please provide a detailed title (e.g. "Broker crashes when using TopN query with Bound filter" instead of just "Broker crashes"). ### all versions The Druid version where the problem was encountered. ### SQLMetadataSegmentManager.poll is executed periodly to synchronize segment metadata with metadatabase, and a segment disable request to coordinator will trigger SQLMetadataSegmentManager.removeSegment. There is a thread safe problem in this scenario. Problem triggering process： 1. SQLMetadataSegmentManager.poll polls all segments from druid_segments, but not set it into refDataSources yet. 2. Some one send a disable request of the last used segment to coordinator, SQLMetadataSegmentManager.removeSegment updated the database and removed it from refDataSources. 3. SQLMetadataSegmentManager.poll set the segments into refDataSources and now refDataSources still contains the segment which had been removed by SQLMetadataSegmentManager.removeSegment. 4. Then SQLMetadataSegmentManager.poll will always got empty segment list from database and will not set it into refDataSources. 5. Therefore, coordinator will never drop the removed segment.
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