[
https://issues.apache.org/jira/browse/HBASE-16744?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
stack updated HBASE-16744:
--------------------------
Release Note:
Lock for HBase Entity either a Table, a Namespace, or Regions.
These are remote locks which live on master, and need periodic heartbeats to
keep them alive. (Once we request the lock, internally an heartbeat thread will
be started). If master doesn't receive the heartbeat in time, it'll release the
lock and make it available to other users.
Use {@link LockServiceClient} to build instances. Then call {@link
#requestLock()}. {@link #requestLock} will contact master to queue the lock and
start the heartbeat thread which will check lock's status periodically and once
the lock is acquired, it will send the heartbeats to the master.
Use {@link #await} or {@link #await(long, TimeUnit)} to wait for the lock to be
acquired. Always call {@link #unlock()} irrespective of whether lock was
acquired or not. If the lock was acquired, it'll be released. If it was not
acquired, it is possible that master grants the lock in future and the
heartbeat thread keeps it alive forever by sending heartbeats. Calling {@link
#unlock()} will stop the heartbeat thread and cancel the lock queued on master.
There are 4 ways in which these remote locks may be released/can be lost:
* Call {@link #unlock}.
* Lock times out on master: Can happen because of network issues, GC pauses,
etc. Worker thread will call the given abortable as soon as it detects such a
situation. Fail to contact master: If worker thread can not contact mater and
thus fails to send heartbeat before the timeout expires, it assumes that lock
is lost and calls the
* abortable.
Worker thread is interrupted.
Use example:
EntityLock lock = lockServiceClient.*Lock(...., "exampled lock", abortable);
lock.requestLock();
....
....can do other initializations here since lock is 'asynchronous'...
....
if (lock.await(timeout)) {
....logic requiring mutual exclusion
}
lock.unlock();
was:
Locks for table/namespace/regions. Use {@link LockServiceClient} to build
instances.
These are remote locks which live on master, and need periodic heartbeats to
keep them alive. (Once we requested the lock, internally an heartbeat thread
will be started). If master doesn't receive the heartbeat in time, it'll
release the lock and make it available to other users.
{@link #requestLock} will contact master to queue the lock and start the
heartbeat thread which'll check lock's status periodically and once the lock is
acquired, it will send the heartbeats to the master.
Use {@link #await} or {@link #await(long, TimeUnit)} to wait for the lock to be
acquired. Always call {@link #unlock()} irrespective of whether lock was
acquired or not. If the lock was acquired, it'll be released. If it was not
acquired, it's possible that master grants the lock in future and the heartbeat
thread keeps it alive forever by sending heartbeats. Calling {@link #unlock()}
will stop the heartbeat thread and cancel the lock queued on master.
There are 4 ways in which these remote locks may be released/can be lost:
* Call {@link #unlock}.
* Lock times out on master: Can happen because of network issues, GC pauses,
etc.
* Worker thread will call the given abortable as soon as it detects such a
situation.
* Fail to contact master: If worker thread can not contact mater and thus
fails to send heartbeat before the timeout expires, it assumes that lock is
lost and calls the abortable.
* Worker thread is interrupted.
Use example:
<code>
HBaseLock lock = admin.*Lock(...., "exampled lock", abortable);
lock.queueLock();
....
....can do other initializations here since lock is 'asynchronous'...
....
if (lock.await(timeout)) {
....logic requiring mutual exclusion
}
lock.unlock();
</code>
> Procedure V2 - Lock procedures to allow clients to acquire locks on
> tables/namespaces/regions
> ---------------------------------------------------------------------------------------------
>
> Key: HBASE-16744
> URL: https://issues.apache.org/jira/browse/HBASE-16744
> Project: HBase
> Issue Type: Sub-task
> Reporter: Appy
> Assignee: Matteo Bertozzi
> Attachments: HBASE-16744.master.001.patch,
> HBASE-16744.master.002.patch, HBASE-16744.master.003.patch,
> HBASE-16744.master.004.patch, HBASE-16744.master.005.patch,
> HBASE-16744.master.006.patch, HBASE-16744.master.007.patch,
> HBASE-16744.master.008.patch, HBASE-16744.master.009.patch,
> HBASE-16744.master.010.patch, HBASE-16744.master.011.patch,
> HBASE-16744.master.012.patch, HBASE-16744.master.013.patch,
> HBASE-16744.master.014.patch, HBASE-16744.master.015.patch,
> HBASE-16744.master.016.patch, HBASE-16744.master.017.patch
>
>
> Will help us get rid of ZK locks.
> Will be useful for external tools like hbck, future backup manager, etc.
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
