[HBASE-22459] Expose store reader reference count

• Type: Improvement
• Status: Resolved
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.0.0-alpha-1, 1.5.0, 2.3.0
• Component/s: HFile, metrics, regionserver
• Hadoop Flags: Reviewed
• Release Note: This change exposes the aggregate count of store reader references for a given store as 'storeRefCount' in region metrics and ClusterStatus.
• Assignee: Andrew Kyle Purtell
• Reporter: Andrew Kyle Purtell
• Created: 22/May/19 21:46
• Updated: 21/Jun/19 09:40
• Resolved: 30/May/19 22:06

Description

Expose the reference count over a region's store file readers as a metric in region metrics and also as a new field in RegionLoad. This will make visible the reader reference count over all stores in the region to both metrics capture and anything that consumes ClusterStatus, like the shell's status command and the master UI.

Coprocessors that wrap scanners might leak them, which will leak readers. We log when this happens but in order to notice the increasing trend of reference counts you have to scrape log output. It would be better if this information is also available as a metric.

Issue Links

• is related to: HBASE-22457 Harden the HBase HFile reader reference counting
• relates to: PHOENIX-5296 Ensure store file reader refcount is zero at end of relevant unit tests
• links to: GitHub Pull Request #248