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https://issues.apache.org/jira/browse/ZOOKEEPER-2867?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16495919#comment-16495919
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Michael Han commented on ZOOKEEPER-2867:
----------------------------------------
[~junrao] - ok, finally get back to this :=).
I checked the broker 1 and 2's commit log, session {{0x25cd1e82c110001}} was
referenced after the "session close" log statement. For example, in server 1's
log file, the first reference of the session 0x25cd1e82c110001 after it's
"closed" is:
{quote}6/27/17 3:05:20 PM PDT session 0x25cd1e82c110001 cxid 0xdc zxid
0x30000047b setData
'/cp15/brokers/topics/xxxx/state,#7b22636f6e74726f6c6c65725f65706f6368223a312c226c6561646572223a302c2276657273696f6e223a312c226c65616465725f65706f6368223a352c22697372223a5b302c315d7d,10
{quote}
Similarly for server 2's commit log session 0x25cd1e82c110001 is referenced
after the "closed" statement as well.
I think in this case session 0x25cd1e82c110001 is not get closed. It could be
that the close requests were sent to server 1 and 2 and then something happened
so the close requests never committed. Note the "close session" entry in the
commit log is missing some context so I can't really tell where this log
statement was from - if we have more detailed log such to indicate where this
log statement was coming from, I might be able to tell the state of the server
at that time.
One way to make sure the close session proposal really gets committed across
the quorum is to looking for this log statement (need to enable debug logging):
[https://github.com/apache/zookeeper/blob/branch-3.4/src/java/main/org/apache/zookeeper/server/quorum/CommitProcessor.java#L164]
At this point, the proposal reached consensus and is persistent across a quorum
of nodes (the state change might not yet applied to the data tree, but as long
as the proposal is persistent we are fine).
> an expired ZK session can be re-established
> -------------------------------------------
>
> Key: ZOOKEEPER-2867
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-2867
> Project: ZooKeeper
> Issue Type: Bug
> Affects Versions: 3.4.10
> Reporter: Jun Rao
> Assignee: Michael Han
> Priority: Major
> Attachments: 0.parsed_commit_log, 1.parsed_commit_log,
> 2.parsed_commit_log, zk.0.08-02, zk.0.08-02, zk.0.formatted, zk.1.08-02,
> zk.1.08-02, zk.1.formatted, zk.2.08-02, zk.2.08-02
>
>
> Not sure if this is a real bug, but I found an instance when a ZK client
> seems to be able to renew a session already expired by the ZK server.
> From ZK server log, session 25cd1e82c110001 was expired at 22:04:39.
> {code:java}
> June 27th 2017, 22:04:39.000 INFO
> org.apache.zookeeper.server.ZooKeeperServer Expiring session
> 0x25cd1e82c110001, timeout of 12000ms exceeded
> June 27th 2017, 22:04:39.001 DEBUG
> org.apache.zookeeper.server.quorum.Leader Proposing::
> sessionid:0x25cd1e82c110001 type:closeSession cxid:0x0 zxid:0x200000fc4
> txntype:-11 reqpath:n/a
> June 27th 2017, 22:04:39.001 INFO
> org.apache.zookeeper.server.PrepRequestProcessor Processed session
> termination for sessionid: 0x25cd1e82c110001
> June 27th 2017, 22:04:39.001 DEBUG
> org.apache.zookeeper.server.quorum.CommitProcessor Processing request::
> sessionid:0x25cd1e82c110001 type:closeSession cxid:0x0 zxid:0x200000fc4
> txntype:-11 reqpath:n/a
> June 27th 2017, 22:05:20.324 INFO
> org.apache.zookeeper.server.quorum.Learner Revalidating client:
> 0x25cd1e82c110001
> June 27th 2017, 22:05:20.324 INFO
> org.apache.zookeeper.server.ZooKeeperServer Client attempting to renew
> session 0x25cd1e82c110001 at /100.96.5.6:47618
> June 27th 2017, 22:05:20.325 INFO
> org.apache.zookeeper.server.ZooKeeperServer Established session
> 0x25cd1e82c110001 with negotiated timeout 12000 for client /100.96.5.6:47618
> {code}
> From ZK client's log, it was able to renew the expired session on 22:05:20.
> {code:java}
> June 27th 2017, 22:05:18.590 INFO org.apache.zookeeper.ClientCnxn Client
> session timed out, have not heard from server in 4485ms for sessionid
> 0x25cd1e82c110001, closing socket connection and attempting reconnect 0
> June 27th 2017, 22:05:18.590 WARN org.apache.zookeeper.ClientCnxn Client
> session timed out, have not heard from server in 4485ms for sessionid
> 0x25cd1e82c110001 0
> June 27th 2017, 22:05:19.325 WARN org.apache.zookeeper.ClientCnxn SASL
> configuration failed: javax.security.auth.login.LoginException: No JAAS
> configuration section named 'Client' was found in specified JAAS
> configuration file: '/opt/confluent/etc/kafka/server_jaas.conf'. Will
> continue connection to Zookeeper server without SASL authentication, if
> Zookeeper server allows it. 0
> June 27th 2017, 22:05:19.326 INFO org.apache.zookeeper.ClientCnxn Opening
> socket connection to server 100.65.188.168/100.65.188.168:2181 0
> June 27th 2017, 22:05:20.324 INFO org.apache.zookeeper.ClientCnxn Socket
> connection established to 100.65.188.168/100.65.188.168:2181, initiating
> session 0
> June 27th 2017, 22:05:20.327 INFO org.apache.zookeeper.ClientCnxn Session
> establishment complete on server 100.65.188.168/100.65.188.168:2181,
> sessionid = 0x25cd1e82c110001, negotiated timeout = 12000 0
> {code}
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