[HBASE-3336] Make GC pauses more obvious to users

• Type: Improvement
• Status: Closed
• Priority: Major
• Resolution: Implemented
• Affects Version/s: 0.92.0
• Component/s: regionserver
• Assignee: Unassigned
• Reporter: Todd Lipcon
• Created: 13/Dec/10 08:00
• Updated: 12/Jun/22 00:16
• Resolved: 24/Dec/14 19:48

Description

We often see users hit GC pauses, but it's not obvious to them what happened. I propose we add a "GCMonitor" thread which wakes up every few seconds and checks (a) that it slept for around the right amount of time, and (b) uses the JVM GC metrics to see if there was a long pause. If a long pause is detected we should output a very loud and obnoxious message to the logs indicating that a length GC pause occurred, and point to a wiki page on the topic.