[OAK-5117] Improve checkMemory for compaction

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.5.14, 1.6.0
• Component/s: segment-tar
• Flags: Patch
• Assignee: Alex Deparvu
• Reporter: Valentin Olteanu
• Created: 16/Nov/16 14:00
• Updated: 06/Dec/16 10:37
• Resolved: 16/Nov/16 16:23

Description

The check introduced in OAK-4966 is relying on the first MemoryPoolMXBean found that matches the criteria. This means that, depending on the JVM, it will be checking any of the: PS Eden Space, PS Survivor Space or PS Old Gen Space - whichever is found first.

I am proposing a more reliable way to check this:
1. check the biggest pool - this usually corresponds to PS Old Gen (by default 2/3 of the heap), which is more stable and reflects better the usage of the heap.
2. use getCollectionUsage() instead of getUsage() to check the state of the heap after a GC. This way we avoid checking during temporary peaks of the used heap.

Issue Links

• relates to: OAK-4966 Re-introduce a blocker for compaction based on available heap