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From German Blanco <german.blanco.bla...@gmail.com>
Subject Re: zk server falling apart from quorum due to connection loss and couldn't connect back
Date Sun, 26 Jan 2014 09:53:52 GMT
Hello Deepak,

sorry for the slow response.
I can't figure out what might be going on here without the log files.
The traces you see in S2 do not indicate any problem, as far as I see. It
seems that you have a client running in S2 that tries to connect to that
server. Since S2 hasn't been able to join a quorum, the server attending
clients hasn't been started and the connection is rejected.
Maybe, to start with, you could start by uploading the traces around the
connection loss between S2 and S3 (say a couple of minutes before and
after).

Regards,

German.


On Thu, Jan 23, 2014 at 8:42 PM, Deepak Jagtap <deepak.jagtap@maxta.com>wrote:

> Hi,
>
> zoo.cfg is :
>
> maxClientCnxns=50
> # The number of milliseconds of each tick
> tickTime=2000
> # The number of ticks that the initial
> # synchronization phase can take
> initLimit=10
> # The number of ticks that can pass between
> # sending a request and getting an acknowledgement
> syncLimit=5
> # the directory where the snapshot is stored.
> dataDir=/var/lib/zookeeper
> # the port at which the clients will connect
> clientPort=2181
>
> autopurge.snapRetainCount=3
> autopurge.purgeInterval=1
> dynamicConfigFile=/etc/maxta/zookeeper/conf/zoo.cfg.dynamic
>
>
>
> zoo.cfg.dynamic is:
>
> server.1=169.254.1.1:2888:3888:participant;0.0.0.0:2181
> server.2=169.254.1.2:2888:3888:participant;0.0.0.0:2181
> server.3=169.254.1.3:2888:3888:participant;0.0.0.0:2181
> version=1
>
>
> Thanks & Regards,
> Deepak
>
>
> On Thu, Jan 23, 2014 at 11:30 AM, German Blanco <
> german.blanco.blanco@gmail.com> wrote:
>
> > Sorry but the attachment didn't make it through.
> > It might be safer to put the files somewhere in the web and send a link.
> >
> >
> > On Thu, Jan 23, 2014 at 8:00 PM, Deepak Jagtap <deepak.jagtap@maxta.com
> > >wrote:
> >
> > > Hi German,
> > >
> > > Please find zookeeper config files attached.
> > >
> > > Thanks & Regards,
> > > Deepak
> > >
> > >
> > > On Thu, Jan 23, 2014 at 12:59 AM, German Blanco <
> > > german.blanco.blanco@gmail.com> wrote:
> > >
> > >> Hello!
> > >>
> > >> Could you please post your configuration files?
> > >>
> > >> Regards,
> > >>
> > >> German.
> > >>
> > >>
> > >> On Thu, Jan 23, 2014 at 2:28 AM, Deepak Jagtap <
> deepak.jagtap@maxta.com
> > >> >wrote:
> > >>
> > >> > Hi All,
> > >> >
> > >> > We have deployed zookeeper version 3.5.0.1515976, with 3 zk servers
> in
> > >> the
> > >> > quorum.
> > >> > The problem we are facing is that one zookeeper server in the quorum
> > >> falls
> > >> > apart, and never becomes part of the cluster until we restart
> > zookeeper
> > >> > server on that node.
> > >> >
> > >> > Our interpretation from zookeeper logs on all nodes is as follows:
> > >> > (For simplicity assume S1=> zk server1, S2 => zk server2, S3
=> zk
> > >> server
> > >> > 3)
> > >> > Initially S3 is the leader while S1 and S2 are followers.
> > >> >
> > >> > S2 hits 46 sec latency while fsyncing write ahead log and results
in
> > >> loss
> > >> > of connection with S3.
> > >> >  S3 in turn prints following error message:
> > >> >
> > >> > Unexpected exception causing shutdown while sock still open
> > >> > java.net.SocketTimeoutException: Read timed out
> > >> > Stack trace
> > >> > ******* GOODBYE /169.254.1.2:47647(S2) ********
> > >> >
> > >> > S2 in this case closes connection with S3(leader) and shuts down
> > >> follower
> > >> > with following log messages:
> > >> > Closing connection to leader, exception during packet send
> > >> > java.net.SocketException: Socket close
> > >> > Follower@194] - shutdown called
> > >> > java.lang.Exception: shutdown Follower
> > >> >
> > >> > After this point S3 could never reestablish connection with S2 and
> > >> leader
> > >> > election mechanism keeps failing. S3 now keeps printing following
> > >> message
> > >> > repeatedly:
> > >> > Cannot open channel to 2 at election address /169.254.1.2:3888
> > >> > java.net.ConnectException: Connection refused.
> > >> >
> > >> > While S3 is in this state, S2 repeatedly keeps printing following
> > >> message:
> > >> > INFO [NIOServerCxnFactory.AcceptThread:/0.0.0.0:2181
> > >> > :NIOServerCnxnFactory$AcceptThread@296] - Accepted socket
> connection
> > >> from
> > >> > /
> > >> > 127.0.0.1:60667
> > >> > Exception causing close of session 0x0: ZooKeeperServer not running
> > >> > Closed socket connection for client /127.0.0.1:60667 (no session
> > >> > established for client)
> > >> >
> > >> > Leader election never completes successfully and causing S2 to fall
> > >> apart
> > >> > from the quorum.
> > >> > S2 was out of quorum for almost 1 week.
> > >> >
> > >> > While debugging this issue, we found out that both election and peer
> > >> > connection ports on S2  can't be telneted from any of the node (S1,
> > S2,
> > >> > S3). Network connectivity is not the issue. Later, we restarted the
> ZK
> > >> > server S2 (service zookeeper-server restart) -- now we could telnet
> to
> > >> both
> > >> > the ports and S2 joined the ensemble after a leader election
> attempt.
> > >> > Any idea what might be forcing S2 to get into a situation where it
> > won't
> > >> > accept any connections on the leader election and peer connection
> > ports?
> > >> >
> > >> > Should I file a jira on this and upload all log files while
> submitting
> > >> the
> > >> > jira as log files are close to 250MB each?
> > >> >
> > >> > Thanks & Regards,
> > >> > Deepak
> > >> >
> > >>
> > >
> > >
> >
>

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