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https://issues.apache.org/jira/browse/ZOOKEEPER-2172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14642415#comment-14642415
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Hitoshi Mitake commented on ZOOKEEPER-2172:
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Hi [~ziyouw],
Could you check my understanding is correct? IIUC, your situation is like below:
1. server 1 boot
2. server 2 boot
3. client issues reconfig to server 1
4. server 2 tries to sync with server 1 with Learner.syncWithLeader()
5. server 3 boot
6. client issues reconfig to server 1
(reconfig requests in 3 and 6 are overwrapping)
Is this correct, I'll be able to reproduce the situation with earthquake.
> Cluster crashes when reconfig a new node as a participant
> ---------------------------------------------------------
>
> Key: ZOOKEEPER-2172
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2172
> Project: ZooKeeper
> Issue Type: Bug
> Components: leaderElection, quorum, server
> Affects Versions: 3.5.0
> Environment: Ubuntu 12.04 + java 7
> Reporter: Ziyou Wang
> Priority: Critical
> Attachments: history.txt, node-1.log, node-2.log, node-3.log,
> zoo-1.log, zoo-2-1.log, zoo-2-2.log, zoo-2-3.log, zoo-2.log, zoo-2212-1.log,
> zoo-2212-2.log, zoo-2212-3.log, zoo-3-1.log, zoo-3-2.log, zoo-3-3.log,
> zoo-3.log, zoo-4-1.log, zoo-4-2.log, zoo-4-3.log, zoo.cfg.dynamic.10000005d,
> zoo.cfg.dynamic.next, zookeeper-1.log, zookeeper-1.out, zookeeper-2.log,
> zookeeper-2.out, zookeeper-3.log, zookeeper-3.out
>
>
> The operations are quite simple: start three zk servers one by one, then
> reconfig the cluster to add the new one as a participant. When I add the
> third one, the zk cluster may enter a weird state and cannot recover.
>
> I found “2015-04-20 12:53:48,236 [myid:1] - INFO [ProcessThread(sid:1
> cport:-1)::PrepRequestProcessor@547] - Incremental reconfig” in node-1 log.
> So the first node received the reconfig cmd at 12:53:48. Latter, it logged
> “2015-04-20 12:53:52,230 [myid:1] - ERROR
> [LearnerHandler-/10.0.0.2:55890:LearnerHandler@580] - Unexpected exception
> causing shutdown while sock still open” and “2015-04-20 12:53:52,231 [myid:1]
> - WARN [LearnerHandler-/10.0.0.2:55890:LearnerHandler@595] - ******* GOODBYE
> /10.0.0.2:55890 ********”. From then on, the first node and second node
> rejected all client connections and the third node didn’t join the cluster as
> a participant. The whole cluster was done.
>
> When the problem happened, all three nodes just used the same dynamic
> config file zoo.cfg.dynamic.10000005d which only contained the first two
> nodes. But there was another unused dynamic config file in node-1 directory
> zoo.cfg.dynamic.next which already contained three nodes.
>
> When I extended the waiting time between starting the third node and
> reconfiguring the cluster, the problem didn’t show again. So it should be a
> race condition problem.
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