[HBASE-27186] Report block cache size metrics separately for L1 and L2

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.5.0, 3.0.0-alpha-4, 2.4.14
• Assignee: Bryan Beaudreault
• Reporter: Bryan Beaudreault
• Created: 08/Jul/22 20:24
• Updated: 13/Jul/22 05:32
• Resolved: 12/Jul/22 02:19

Description

Currently, in terms of block cache size metrics, we report the following: blockCacheFreeSize, blockCacheCount, blockCacheSize, blockCacheEvictionCount. This isn't super useful when running with BucketCache, because in that case L1 (holding index/meta blocks) and L2 (holding data blocks) operate largely independently. Additionally, you might typically report on block cache sizes in terms of monitoring heap usage. But with BucketCache, the cache is off-heap, so it becomes a misleading metric in that case.

We have metrics l1CacheHitCount/MissCount/HitRatio/MissRatio, and the same for l2. We should add l1CacheFreeSize, l1CacheSize, l1CacheCount, l1CacheEvictionCount, and the same for l2.

Issue Links

• links to: GitHub Pull Request #4608