[HBASE-4089] blockCache contents report

• Type: New Feature
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 0.99.0
• Hadoop Flags: Reviewed

Release Note

Show more detail on blockcache deployed in new BlockCache section under Tasks and above Regions; shows blockcache type, what for L1 and L2, help pointers, type-specific and L1/L2 stats as well as dumps of bucket/slab cache stats when bucket/slabs enabled. Keeps block cache age (works in Bucket and LruBlockCache, not for Slab). Adds JSON page with details on block caches and a facility for listing block cache content by file (useful finding hot files).

• Assignee: Michael Stack
• Reporter: Doug Meil
• Created: 12/Jul/11 20:47
• Updated: 21/Feb/15 23:33
• Resolved: 09/Jun/14 23:49

Description

Summarized block-cache report for a RegionServer would be helpful. For example ...

table1
cf1 100 blocks, totalBytes=yyyyy, averageTimeInCache=XXXX hours
cf2 200 blocks, totalBytes=zzzzz, averageTimeInCache=XXXX hours

table2
cf1 75 blocks, totalBytes=yyyyy, averageTimeInCache=XXXX hours
cf2 150 blocks, totalBytes=zzzzz, averageTimeInCache=XXXX hours

... Etc.

The current metrics list blockCacheSize and blockCacheFree, but there is no way to know what's in there. Any single block isn't really important, but the patterns of what CF/Table they came from, how big are they, and how long (on average) they've been in the cache, are important.

No such interface exists in HRegionInterface. But I think it would be helpful from an operational perspective.

Updated (7-29): Removing suggestion for UI. I would be happy just to get this report on a configured interval dumped to a log file.

Sub-Tasks

• blockCache summary - backend: Closed
• blockCache summary - web UI: Closed
• Document blockCache contents report in the UI: Closed