[OAK-4015] Expedite commits from the compactor

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Segment Tar 0.0.12
• Component/s: segment-tar
• Labels: compaction gc perfomance
• Epic Link: SegmentMK revision GC
• Assignee: Michael Dürig
• Reporter: Michael Dürig
• Created: 12/Feb/16 15:42
• Updated: 10/Oct/16 09:49
• Resolved: 08/Sep/16 12:13

Description

Concurrent commits during compaction cause those to be re-compacted. Currently it seems that the compaction thread can end up waiting for some time to acquire the commit lock [1], which in turn causes more commits to pile up to be re-compacted. I think this could be improved by tweaking the lock such that the compactor could jump ahead of the queue. I.e. use a lock which can be acquired in expedited mode.

[1] SegmentNodeStore#commitSemaphore

Issue Links

• depends upon: OAK-4122 Replace the commit semaphore in the segment node store with a scheduler
• is blocked by: OAK-4256 CLONE - Cross gc sessions might introduce references to pre-compacted segments
• is blocked by: OAK-3348 Cross gc sessions might introduce references to pre-compacted segments