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https://issues.apache.org/jira/browse/ZOOKEEPER-1367?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13192870#comment-13192870
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Jeremy Stribling commented on ZOOKEEPER-1367:
---------------------------------------------
{quote}
so when you say that you only add or remove one node at a time. does that mean
you:
1) have a running cluster
2) take it done
3) change the configuration to add a node
4) start the cluster back up
5) wait until a leader becomes active
you only add or remove the next steps after you have completed all 5 steps for
the previous configuration?
{quote}
That's more or less correct, except that steps 2-5 are being executed in
parallel on all the nodes to speed things up, so they are not proceeding in
lockstep across the cluster. We wait for all nodes to complete the 5 steps
before moving on to the next node, if there is one.
I am still working on getting this reproduced by QA. They said they've fixed
the NTP issues, so hopefully the new logs will be easier to work with if we can
get it to happen again.
> Data inconsistencies and unexpired ephemeral nodes after cluster restart
> ------------------------------------------------------------------------
>
> Key: ZOOKEEPER-1367
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1367
> Project: ZooKeeper
> Issue Type: Bug
> Components: server
> Affects Versions: 3.4.2
> Environment: Debian Squeeze, 64-bit
> Reporter: Jeremy Stribling
> Priority: Blocker
> Fix For: 3.4.3
>
> Attachments: ZOOKEEPER-1367.tgz
>
>
> In one of our tests, we have a cluster of three ZooKeeper servers. We kill
> all three, and then restart just two of them. Sometimes we notice that on
> one of the restarted servers, ephemeral nodes from previous sessions do not
> get deleted, while on the other server they do. We are effectively running
> 3.4.2, though technically we are running 3.4.1 with the patch manually
> applied for ZOOKEEPER-1333 and a C client for 3.4.1 with the patches for
> ZOOKEEPER-1163.
> I noticed that when I connected using zkCli.sh to the first node (90.0.0.221,
> zkid 84), I saw only one znode in a particular path:
> {quote}
> [zk: 90.0.0.221:2888(CONNECTED) 0] ls /election/zkrsm
> [nominee0000000011]
> [zk: 90.0.0.221:2888(CONNECTED) 1] get /election/zkrsm/nominee0000000011
> 90.0.0.222:7777
> cZxid = 0x400000027
> ctime = Thu Jan 19 08:18:24 UTC 2012
> mZxid = 0x400000027
> mtime = Thu Jan 19 08:18:24 UTC 2012
> pZxid = 0x400000027
> cversion = 0
> dataVersion = 0
> aclVersion = 0
> ephemeralOwner = 0xa234f4f3bc220001
> dataLength = 16
> numChildren = 0
> {quote}
> However, when I connect zkCli.sh to the second server (90.0.0.222, zkid 251),
> I saw three znodes under that same path:
> {quote}
> [zk: 90.0.0.222:2888(CONNECTED) 2] ls /election/zkrsm
> nominee0000000006 nominee0000000010 nominee0000000011
> [zk: 90.0.0.222:2888(CONNECTED) 2] get /election/zkrsm/nominee0000000011
> 90.0.0.222:7777
> cZxid = 0x400000027
> ctime = Thu Jan 19 08:18:24 UTC 2012
> mZxid = 0x400000027
> mtime = Thu Jan 19 08:18:24 UTC 2012
> pZxid = 0x400000027
> cversion = 0
> dataVersion = 0
> aclVersion = 0
> ephemeralOwner = 0xa234f4f3bc220001
> dataLength = 16
> numChildren = 0
> [zk: 90.0.0.222:2888(CONNECTED) 3] get /election/zkrsm/nominee0000000010
> 90.0.0.221:7777
> cZxid = 0x30000014c
> ctime = Thu Jan 19 07:53:42 UTC 2012
> mZxid = 0x30000014c
> mtime = Thu Jan 19 07:53:42 UTC 2012
> pZxid = 0x30000014c
> cversion = 0
> dataVersion = 0
> aclVersion = 0
> ephemeralOwner = 0xa234f4f3bc220000
> dataLength = 16
> numChildren = 0
> [zk: 90.0.0.222:2888(CONNECTED) 4] get /election/zkrsm/nominee0000000006
> 90.0.0.223:7777
> cZxid = 0x200000cab
> ctime = Thu Jan 19 08:00:30 UTC 2012
> mZxid = 0x200000cab
> mtime = Thu Jan 19 08:00:30 UTC 2012
> pZxid = 0x200000cab
> cversion = 0
> dataVersion = 0
> aclVersion = 0
> ephemeralOwner = 0x5434f5074e040002
> dataLength = 16
> numChildren = 0
> {quote}
> These never went away for the lifetime of the server, for any clients
> connected directly to that server. Note that this cluster is configured to
> have all three servers still, the third one being down (90.0.0.223, zkid 162).
> I captured the data/snapshot directories for the the two live servers. When
> I start single-node servers using each directory, I can briefly see that the
> inconsistent data is present in those logs, though the ephemeral nodes seem
> to get (correctly) cleaned up pretty soon after I start the server.
> I will upload a tar containing the debug logs and data directories from the
> failure. I think we can reproduce it regularly if you need more info.
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