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From "Michael Han (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (ZOOKEEPER-2867) an expired ZK session can be re-established
Date Mon, 21 Aug 2017 02:11:03 GMT

    [ https://issues.apache.org/jira/browse/ZOOKEEPER-2867?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16134630#comment-16134630
] 

Michael Han commented on ZOOKEEPER-2867:
----------------------------------------

bq. the old ZK session for broker 0 (25cd1e82c110001) should be expired after the ZK servers
were restarted (but it didn't seem to happen). 

The expected behavior in this case is actually opposite: when ZK servers restarts, as long
as clients, including broker 0 can reconnect to ZK within the configured time limits, the
session will be renewed. This is because when ZK server restarts (or when it loses quorum
during LE), the clock used for session timeout stops ticking until a new quorum is formed.
In this case the ZK servers were down (23:16) before broker 0 is down (23:17) so it's totally
possible for broker 0 to renew the session.

bq. In ZK server 1's commit log, I saw the following, which indicates that session 25cd1e82c110001
was closed.

Could you please point to me the file name of the attached log that appertains to this? I
don't find the file (the latest attached log file has dates as 8/02 instead of 6/27).

> 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
>         Attachments: 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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