Details
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.