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https://issues.apache.org/jira/browse/ZOOKEEPER-2247?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14701139#comment-14701139
]
Rakesh R commented on ZOOKEEPER-2247:
-------------------------------------
Thanks [~arshad.mohammad] for the analysis. IMHO we should handle QuorumPeer
and Standalone separately. One approach I'm thinking is, presently
{{ZooKeeperServerListenerImpl}} is inside ZooKeeperServer.java we can move this
to a separate java file.
.
- *Standalone* server can use this one, here instead of zks#shutdown() we
should think of interrupting {{cnxnFactory}} and {{secureCnxnFactory}} and
gracefully bring down the server.
- *QuorumPeer* can do {{QuorumPeerListenerImpl extends
ZooKeeperServerListenerImpl}} and stop respective observer/follower/leader
service. This way will make the server to LOOKING state and allows to continue
with the internal leader-election. This is similar to a situation where
QuorumPeer hits unexpected exception and giving another chance to join quorum.
Please refer below switch case logic, which is similar to the finally block of
each
[QuorumPeer#L1055|https://github.com/apache/zookeeper/blob/trunk/src/java/main/org/apache/zookeeper/server/quorum/QuorumPeer.java#L1055]
server respectively.
{code}
QuorumPeer#stopService(){
switch (getPeerState()) {
case OBSERVING:
// stopObserver();
observer.shutdown();
setObserver(null);
updateServerState();
break;
case FOLLOWING:
// stopFollower();
follower.shutdown();
setFollower(null);
updateServerState();
break;
case LEADING:
// stopLeader();
if (leader != null) {
leader.shutdown("Forcing shutdown");
setLeader(null);
}
updateServerState();
break;
}
}
{code}
> Zookeeper service becomes unavailable when leader fails to write transaction
> log
> --------------------------------------------------------------------------------
>
> Key: ZOOKEEPER-2247
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2247
> Project: ZooKeeper
> Issue Type: Bug
> Affects Versions: 3.5.0
> Reporter: Arshad Mohammad
> Assignee: Arshad Mohammad
> Priority: Critical
> Fix For: 3.5.2
>
>
> Zookeeper service becomes unavailable when leader fails to write transaction
> log. Bellow are the exceptions
> {code}
> 2015-08-14 15:41:18,556 [myid:100] - ERROR
> [SyncThread:100:ZooKeeperCriticalThread@48] - Severe unrecoverable error,
> from thread : SyncThread:100
> java.io.IOException: Input/output error
> at sun.nio.ch.FileDispatcherImpl.force0(Native Method)
> at sun.nio.ch.FileDispatcherImpl.force(FileDispatcherImpl.java:76)
> at sun.nio.ch.FileChannelImpl.force(FileChannelImpl.java:376)
> at
> org.apache.zookeeper.server.persistence.FileTxnLog.commit(FileTxnLog.java:331)
> at
> org.apache.zookeeper.server.persistence.FileTxnSnapLog.commit(FileTxnSnapLog.java:380)
> at org.apache.zookeeper.server.ZKDatabase.commit(ZKDatabase.java:563)
> at
> org.apache.zookeeper.server.SyncRequestProcessor.flush(SyncRequestProcessor.java:178)
> at
> org.apache.zookeeper.server.SyncRequestProcessor.run(SyncRequestProcessor.java:113)
> 2015-08-14 15:41:18,559 [myid:100] - INFO
> [SyncThread:100:ZooKeeperServer$ZooKeeperServerListenerImpl@500] - Thread
> SyncThread:100 exits, error code 1
> 2015-08-14 15:41:18,559 [myid:100] - INFO
> [SyncThread:100:ZooKeeperServer@523] - shutting down
> 2015-08-14 15:41:18,560 [myid:100] - INFO
> [SyncThread:100:SessionTrackerImpl@232] - Shutting down
> 2015-08-14 15:41:18,560 [myid:100] - INFO
> [SyncThread:100:LeaderRequestProcessor@77] - Shutting down
> 2015-08-14 15:41:18,560 [myid:100] - INFO
> [SyncThread:100:PrepRequestProcessor@1035] - Shutting down
> 2015-08-14 15:41:18,560 [myid:100] - INFO
> [SyncThread:100:ProposalRequestProcessor@88] - Shutting down
> 2015-08-14 15:41:18,561 [myid:100] - INFO
> [SyncThread:100:CommitProcessor@356] - Shutting down
> 2015-08-14 15:41:18,561 [myid:100] - INFO
> [CommitProcessor:100:CommitProcessor@191] - CommitProcessor exited loop!
> 2015-08-14 15:41:18,562 [myid:100] - INFO
> [SyncThread:100:Leader$ToBeAppliedRequestProcessor@915] - Shutting down
> 2015-08-14 15:41:18,562 [myid:100] - INFO
> [SyncThread:100:FinalRequestProcessor@646] - shutdown of request processor
> complete
> 2015-08-14 15:41:18,562 [myid:100] - INFO
> [SyncThread:100:SyncRequestProcessor@191] - Shutting down
> 2015-08-14 15:41:18,563 [myid:100] - INFO [ProcessThread(sid:100
> cport:-1)::PrepRequestProcessor@159] - PrepRequestProcessor exited loop!
> {code}
> After this exception Leader server still remains leader. After this non
> recoverable exception the leader should go down and let other followers
> become leader.
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