[HBASE-15931] Add log for long-running tasks in AsyncProcess

• Type: Improvement
• Status: Resolved
• Priority: Critical
• Resolution: Fixed
• Fix Version/s: 1.3.0, 0.98.20, 1.1.6, 1.2.3, 2.0.0, 1.2.7
• Component/s: Operability
• Hadoop Flags: Reviewed

Release Note

After HBASE-15931, we will log more details for long-running tasks in AsyncProcess#waitForMaximumCurrentTasks every 10 seconds, including:
1. Table name will be included in the tasks status log
2. On which regionserver(s) the tasks are runnning will be logged when less than hbase.client.threshold.log.details tasks left, by default 10.
3. Against which regions the tasks are running will be logged when less than 2 tasks left.

• Assignee: Yu Li
• Reporter: Yu Li
• Created: 01/Jun/16 09:24
• Updated: 06/Sep/18 19:10
• Resolved: 03/Jun/16 11:43

Description

Currently if there's any long-tail tasks in a multi-action request like triggered by BufferedMutatorImpl#backgroundFlushCommits, we could see logging message like below

2016-05-31 09:36:55,461 INFO [Thread-16] org.apache.hadoop.hbase.client.AsyncProcess: #28, waiting for some tasks to finish. Expected max=0, tasksInProgress=1

but there's no way to know detail of this long-tail, such as which table/region it's accessing. This JIRA aims at adding such log for easier debugging.