[OAK-3177] Compaction slow on repository with continuous writes

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.3.4, 1.4
• Component/s: segmentmk
• Labels: compaction gc
• Epic Link: SegmentMK revision GC
• Assignee: Michael Dürig
• Reporter: Michael Dürig
• Created: 04/Aug/15 14:58
• Updated: 16/Feb/21 09:53
• Resolved: 06/Aug/15 13:58

Description

OAK-2734 introduced retry cycles and the option to force compaction when all cycles fail. However OAK-2192 introduced a performance regression: each compaction cycle takes in the order of the size of the repository to complete instead of in the order of the number of remaining changes to compact. This is caused by comparing compacted with pre-compacted node states, which is necessary to avoid mixed segments (aka OAK-2192). To fix the performance regression I propose to pass the compactor an additional node state (the 'onto' state). The diff would then be calculated across the pre compacted states, which performs in the order of number of changes. The changes would then be applied to the 'onto' state, which is a compacted state to avoid mixed segments.

Issue Links

• depends upon: OAK-2734 Compaction does not finish on repository with continuous writes