Yes, this is plausible. But I'm not sure what the solution is. If a zookeeper session disappears, according to the documentation everything associated with that session should also disappear.
So I guess we could catch this error and just ignore it, assuming that the session must be gone anyway? Karl On Tue, Dec 7, 2021 at 8:21 AM Julien Massiera < julien.massi...@francelabs.com> wrote: > Hi, > > the Zookeeper lock error mentioned in the before last comment of this > issue https://issues.apache.org/jira/browse/CONNECTORS-1447: > > FATAL 2017-08-04 09:28:25,855 (Agents idle cleanup thread) - Error tossed: > Can't release lock we don't hold > java.lang.IllegalStateException: Can't release lock we don't hold > at > org.apache.manifoldcf.core.lockmanager.ZooKeeperConnection.releaseLock(ZooKeeperConnection.java:815) > at > org.apache.manifoldcf.core.lockmanager.ZooKeeperLockObject.clearLock(ZooKeeperLockObject.java:218) > at > org.apache.manifoldcf.core.lockmanager.ZooKeeperLockObject.clearGlobalWriteLockNoWait(ZooKeeperLockObject.java:100) > at > org.apache.manifoldcf.core.lockmanager.LockObject.clearGlobalWriteLock(LockObject.java:160) > at > org.apache.manifoldcf.core.lockmanager.LockObject.leaveWriteLock(LockObject.java:141) > at > org.apache.manifoldcf.core.lockmanager.LockGate.leaveWriteLock(LockGate.java:205) > at > org.apache.manifoldcf.core.lockmanager.BaseLockManager.leaveWrite(BaseLockManager.java:1224) > at > org.apache.manifoldcf.core.lockmanager.BaseLockManager.leaveWriteLock(BaseLockManager.java:771) > at > org.apache.manifoldcf.core.connectorpool.ConnectorPool$Pool.pollAll(ConnectorPool.java:670) > at > org.apache.manifoldcf.core.connectorpool.ConnectorPool.pollAllConnectors(ConnectorPool.java:338) > at > org.apache.manifoldcf.agents.transformationconnectorpool.TransformationConnectorPool.pollAllConnectors(TransformationConnectorPool.java:121) > at > org.apache.manifoldcf.agents.system.IdleCleanupThread.run(IdleCleanupThread.java:91) > > is still happening in 2021 with the 2.20 version of MCF. > > Karl, you hypothesized that it could be related to Zookeeper being > restarted while the MCF agent is still running, but after some > investigations, my theory is that it is related to re-established > sessions. Locks are not associated to a process but to a session, and it > could happen that when a session is closed accidentally (interrupted by > exceptions etc), it does not correctly release the locks it sets. When a > new session is created by Zookeeper for the same client, the locks > cannot be released because they belong to an old session and the > exception is thrown ! > > Is it something plausible for you ? I have no knowledge on Zookeeper but > if it is something plausible, then it is worth investigating into the > code to see if everything is correctly done to be sure that all locks > are released when a session is closed/interrupted by a problem. > > Julien > > -- > L'absence de virus dans ce courrier électronique a été vérifiée par le > logiciel antivirus Avast. > https://www.avast.com/antivirus >
