[
https://issues.apache.org/jira/browse/ZOOKEEPER-2307?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14980746#comment-14980746
]
Flavio Junqueira commented on ZOOKEEPER-2307:
---------------------------------------------
I don't see a problem with inverting the order of the operations, but I'm
thinking that these methods that update epochs might need to be synchronized.
The problem you're describing seems to be due to concurrent access.
> ZooKeeper not starting because acceptedEpoch is less than the currentEpoch
> --------------------------------------------------------------------------
>
> Key: ZOOKEEPER-2307
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2307
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Reporter: Arshad Mohammad
> Assignee: Arshad Mohammad
> Priority: Critical
> Fix For: 3.5.2, 3.6.0
>
> Attachments: ZOOKEEPER-2307-01.patch
>
>
> This issue occurred in one of our test environment where disk was being
> changed to read only very frequently.
> The the scenario is as follows:
> # Configure three node ZooKeeper cluster, lets say nodes are A, B and C
> # Start A and B. Both A and B start successfully, quorum is running.
> # Start C, because of IO error C fails to update acceptedEpoch file. But C
> also starts successfully, joins the quorum as follower
> # Stop C
> # Start C, bellow exception with message "The accepted epoch, 0 is less than
> the current epoch, 1" is thrown
> {code}
> 2015-10-29 16:52:32,942 [myid:3] - ERROR [main:QuorumPeer@784] - Unable to
> load database on disk
> java.io.IOException: The accepted epoch, 0 is less than the current epoch, 1
> at
> org.apache.zookeeper.server.quorum.QuorumPeer.loadDataBase(QuorumPeer.java:781)
> at
> org.apache.zookeeper.server.quorum.QuorumPeer.start(QuorumPeer.java:720)
> at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:202)
> at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:139)
> at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:88)
> 2015-10-29 16:52:32,946 [myid:3] - ERROR [main:QuorumPeerMain@111] -
> Unexpected exception, exiting abnormally
> java.lang.RuntimeException: Unable to run quorum server
> at
> org.apache.zookeeper.server.quorum.QuorumPeer.loadDataBase(QuorumPeer.java:785)
> at
> org.apache.zookeeper.server.quorum.QuorumPeer.start(QuorumPeer.java:720)
> at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.runFromConfig(QuorumPeerMain.java:202)
> at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.initializeAndRun(QuorumPeerMain.java:139)
> at
> org.apache.zookeeper.server.quorum.QuorumPeerMain.main(QuorumPeerMain.java:88)
> Caused by: java.io.IOException: The accepted epoch, 0 is less than the
> current epoch, 1
> at
> org.apache.zookeeper.server.quorum.QuorumPeer.loadDataBase(QuorumPeer.java:781)
> {code}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
