Add support for tryLock - non-blocking row lock acquisition
-----------------------------------------------------------
Key: HBASE-2584
URL: https://issues.apache.org/jira/browse/HBASE-2584
Project: Hadoop HBase
Issue Type: Improvement
Components: regionserver
Reporter: Michael Dalton
Fix For: 0.21.0
Currently HBase clients can only acquire row locks via the blocking lockRow()
method in HTable. As ryan described on the mailing list, relying on this method
in rare highly contended situations can lead to (temporary) deadlock. This
deadlock occurs if a client acquires the lock, and a large number of other
clients attempt to acquire the lock and block. Each blocked client awaiting
lock acquisition consumes one of the limited I/O handler threads on the
regionserver. When lock holder wishes to release the lock, he will be unable to
as all I/O threads are currently serving clients that are blocking on lock
acquisition -- and thus no I/O threads are open to process the unlock request.
To avoid deadlock situations such as the one described above, I have added
support for 'tryLock' in HTable (and on the regionservers). The 'tryLock'
method will attempt to acquire a row lock. In the event that a lock is already
held, tryLock immediately returns null rather than blocking and waiting for the
lock to be acquire. Clients can then implement their own backoff/retry policy
to re-acquire the lock, determine their own timeout values, etc based on their
application performance characteristics rather than block on the regionserver
and tie up precious I/O regionserver handler threads for an indefinite amount
of time.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
