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https://issues.apache.org/jira/browse/ZOOKEEPER-2172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14593156#comment-14593156
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Akihiro Suda commented on ZOOKEEPER-2172:
-----------------------------------------
Hi,
It is so interesting that both of servers 1 and 2 timeout at 15:55:08,439 after
reconfig has begun at 15:55:04.
After these timeouts, both {{ZooKeeperServer}} cannot be revived and the
ensemble gets weird.
(However in zoo-3-2.log (Jun 3), server 2 raises {{EOFException}}, not
{{SocketTimeoutException}} at 17:15:31).
These timeouts are raised by [this while
loop|https://github.com/apache/zookeeper/blob/77e46cad03d64530ea53be53f5e38e8f1e7e8eee/src/java/main/org/apache/zookeeper/server/quorum/LearnerHandler.java#L515]
in server 1 and [this while
loop|https://github.com/apache/zookeeper/blob/77e46cad03d64530ea53be53f5e38e8f1e7e8eee/src/java/main/org/apache/zookeeper/server/quorum/Follower.java#L89]
in server 2.
Unfortunately, we are not sure which types of QuorumPacket are triggering these
timeouts.
So I think it might be helpful to add {{LOG.debug(qp.getType())}} at [this
switch|https://github.com/apache/zookeeper/blob/77e46cad03d64530ea53be53f5e38e8f1e7e8eee/src/java/main/org/apache/zookeeper/server/quorum/LearnerHandler.java#L532]
for server 1 and [this
switch|https://github.com/apache/zookeeper/blob/77e46cad03d64530ea53be53f5e38e8f1e7e8eee/src/java/main/org/apache/zookeeper/server/quorum/Follower.java#L114]
for server 2.
Perhaps they are not pinging each other?
[This|https://github.com/apache/zookeeper/blob/77e46cad03d64530ea53be53f5e38e8f1e7e8eee/src/java/main/org/apache/zookeeper/server/quorum/LearnerHandler.java#L924-925]
comment in {{LearnerHandler.ping()}} seems interesting.
{panel}
// If learner hasn't sync properly yet, don't send ping packet
// otherwise, the learner will crash
{panel}
> 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: 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.cfg.dynamic.10000005d, zoo.cfg.dynamic.next, zookeeper-1.log,
> zookeeper-2.log, zookeeper-3.log
>
>
> 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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