[OAK-4293] Refactor / rework compaction gain estimation

• Type: Task
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: Segment Tar 0.0.10
• Component/s: segment-tar
• Labels: gc
• Epic Link: SegmentMK revision GC
• Assignee: Alex Deparvu
• Reporter: Michael Dürig
• Created: 22/Apr/16 19:49
• Updated: 10/Oct/16 09:48
• Resolved: 09/Aug/16 14:31

Description

I think we have to take another look at CompactionGainEstimate and see whether we can up with a more efficient way to estimate the compaction gain. The current implementation is expensive wrt. IO, CPU and cache coherence. If we want to keep an estimation step we need IMO come up with a cheap way (at least 2 orders of magnitude cheaper than compaction). Otherwise I would actually propose to remove the current estimation approach entirely

Issue Links

• blocks: OAK-4309 Align property labels and descriptions in SegmentNodeStoreService
• is depended upon by: OAK-3695 Expose ratio between waste and real data
• is related to: OAK-3362 Estimate compaction based on diff to previous compacted head state
• is related to: OAK-3348 Cross gc sessions might introduce references to pre-compacted segments
• is related to: OAK-4657 Add metric for FileStore cleanup reclaimed size
• is related to: OAK-4729 OSGi config for the size based estimation