[infinispan-issues] [JBoss JIRA] (ISPN-2240) Per-key lock container leads to superfluous TimeoutExceptions on concurrent access to same key

[Ion Savin (JIRA)]

     [ https://issues.jboss.org/browse/ISPN-2240?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Ion Savin updated ISPN-2240:
----------------------------

    Fix Version/s: 7.0.0.Alpha3
                       (was: 7.0.0.Alpha2)

    
> Per-key lock container leads to superfluous TimeoutExceptions on concurrent access to same key
> ----------------------------------------------------------------------------------------------
>
>                 Key: ISPN-2240
>                 URL: https://issues.jboss.org/browse/ISPN-2240
>             Project: Infinispan
>          Issue Type: Bug
>          Components: Transactions
>    Affects Versions: 5.1.6.FINAL, 5.1.x
>            Reporter: Robert Stupp
>            Assignee: Mircea Markus
>            Priority: Critical
>             Fix For: 7.0.0.Alpha3, 7.0.0.Final
>
>         Attachments: ISPN-2240_fix_TimeoutExceptions.patch, somehow.zip
>
>
> Hi,
> I've encountered a lot of TimeoutExceptions just running a load test against an infinispan cluster.
> I tracked down the reason and found out, that the code in org.infinispan.util.concurrent.locks.containers.AbstractPerEntryLockContainer#releaseLock() causes these superfluous TimeoutExceptions.
> A small test case (which just prints out timeouts, too late timeouts and "paints" a lot of dots to the console - more dots/second on the console means better throughput ;-)
> In a short test I extended the class ReentrantPerEntryLockContainer and changed the implementation of releaseLock() as follows:
> {noformat}
>     public void releaseLock(Object lockOwner, Object key) {
>         ReentrantLock l = locks.get(key);
>         if (l != null) {
>             if (!l.isHeldByCurrentThread())
>                 throw new IllegalStateException("Lock for [" + key + "] not held by current thread " + Thread.currentThread());
>             while (l.isHeldByCurrentThread())
>                 unlock(l, lockOwner);
>             if (!l.hasQueuedThreads())
>                 locks.remove(key);
>         }
>         else
>             throw new IllegalStateException("No lock for [" + key + ']');
>     }
> {noformat}
> The main improvement is that locks are not removed from the concurrent map as long as other threads are waiting on that lock.
> If the lock is removed from the map while other threads are waiting for it, they may run into timeouts and force TimeoutExceptions to the client.
> The above methods "paints more dots per second" - means: it gives a better throughput for concurrent accesses to the same key.
> The re-implemented method should also fix some replication timeout exceptions.
> Please, please add this to 5.1.7, if possible.

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators
For more information on JIRA, see: http://www.atlassian.com/software/jira