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https://issues.apache.org/jira/browse/ZOOKEEPER-3920?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17187961#comment-17187961
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Andre Price commented on ZOOKEEPER-3920:
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[~maoling] - That is a good find. It does look like ZOOKEEPER-3829 will fix
much of this. I tried the release-3.6.2 branch and I could not reproduce the
issue with static config and a config like this:
server.1=0.0.0.0:2888:3888;2181
server.2=zoo2:2888:3888;2181
server.3=zoo3:2888:3888;2181
However, the same config has issues when using reconfiguration
(reconfigEnabled=true). In that case killing the leader makes the cluster
unavailable - no leader is able to be elected.
This probably should be a separate bug (maybe one exists already?). Unless I am
missing some other configuration option (or nuanced usage of multi address
support maybe) it does not seem possible to run zookeeper with reconfiguration
in docker using bridge network if the other servers are not also on the same
bridge network (i.e. they need to be on the same docker host - which isn't
feasible for production usage).
But with 3.6.2 (and other releases that have the ZOOKEEPER-3829 fix) using the
bridge network can work if reconfiguration is disabled.
> Zookeeper clients timeout after leader change
> ---------------------------------------------
>
> Key: ZOOKEEPER-3920
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-3920
> Project: ZooKeeper
> Issue Type: Bug
> Components: quorum, server
> Affects Versions: 3.6.1
> Reporter: Andre Price
> Priority: Major
> Attachments: stack.yml, zk_repro.zip
>
>
> [Sorry I believe this is a dupe of
> https://issues.apache.org/jira/browse/ZOOKEEPER-3828 and potentially
> https://issues.apache.org/jira/browse/ZOOKEEPER-3466
> But i am not able to attach files there for some reason so creating a new
> issue which hopefully allows me]
> We are encountering an issue where failing over from the leader results in
> zookeeper clients not being able to connect successfully. They timeout
> waiting for a response from the server. We are attempting to upgrade some
> existing zookeeper clusters from 3.4.14 to 3.6.1 (not sure if relevant but
> stating incase it helps with pinpointing issue) which is effectively blocked
> by this issue. We perform the rolling upgrade (followers first then leader
> last) and it seems to go successfully by all indicators. But we end up in the
> state described in this issue where if the leader changes (either due to
> restart or stopping) the cluster does not seem able to start new sessions.
> I've gathered some TRACE logs from our servers and will attach in the hopes
> they can help figure this out.
> Attached zk_repro.zip which contains the following:
> * zoo.cfg used in one of the instances (they are all the same except for the
> local server's ip being 0.0.0.0 in each)
> * zoo.cfg.dynamic.next (don't think this is used anywhere but is written by
> zookeeper at some point - I think when the first 3.6.1 container becomes
> leader based on the value – the file is in all containers and is the same in
> all as well)
> * s\{1,2,3}_zk.log - logs from each of the 3 servers. Estimated time of
> repro start indicated by "// REPRO START" text and whitespace in logs
> * repro_steps.txt - rough steps executed that result in the server logs
> attached
>
> I'll summarize the repro here also:
> # Initially it appears to be a healthy 3 node ensemble all running 3.6.1.
> Server ids are 1,2,3 and 3 is the leader. Dynamic config/reconfiguration is
> disabled.
> # invoke srvr on each node (to verify setup and also create bookmark in logs)
> # Do a zkCli get of /zookeeper/quota which succeeds
> # Do a restart of the leader (to same image/config) (server 2 now becomes
> leader, 3 is back as follower)
> # Try to perform the same zkCli get which times out (this get is done within
> the container)
> # Try to perform the same zkCli get but from another machine, this also
> times out
> # Invoke srvr on each node again (to verify that 2 is now the
> leader/bookmark)
> # Do a restart of server 2 (3 becomes leader, 2 follower)
> # Do a zkCli get of /zookeeper/quota which succeeds
> # Invoke srvr on each node again (to verify that 3 is leader)
> I tried to keep the other ZK traffic to a minimum but there are likely some
> periodic mntr requests mixed from our metrics scraper.
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