[HBASE-16994] Region report a last flushed sequence id that is less than the previous last flushed sequence id

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Assignee: Unassigned
• Reporter: Lijin Bin
• Created: 02/Nov/16 13:01
• Updated: 03/Nov/16 04:27
• Resolved: 03/Nov/16 01:00

Description

Since append will be published to RingBuffer and handled asynchronously, it's possible that one append (say append-X) of the region handled by RingBufferEventHandler between startCacheFlush and getNextSequenceId, and reset FSHLog#oldestUnflushedStoreSequenceIds which we just cleared in #startCacheFlush. This might disturb ServerManager#flushedSequenceIdByRegion like shown below (assume region-A has two CF: cfA and cfB)

1. flush-A runs to startCacheFlush and it will flush both cfA and cfB, oldestUnflushedStoreSequenceIds of regionA got cleared
2. append-X on cfB handled by RingBufferEventHandler, oldestUnflushedStoreSequenceIds set to 10, for example
3. flush-A runs to getNextSequenceId and returned 11
4. ServerManager#flushedSequenceIdByRegion for regionA set to 11
5. flush-A finishes
6. flush-B starts and only flush cfA, getNextSequenceId returned 10, and flushedSeqId will return 9, and cause warning in ServerManager

Since this append-X will also got flushed, we should clear the oldestUnflushedStoreSequenceIds again to make sure we won't disturb
ServerManager#flushedSequenceIdByRegion.

Issue Links

• is related to: HBASE-11236 Last flushed sequence id is ignored by ServerManager