From: Johannes Zillmann [mailto:[EMAIL PROTECTED]
Sent: Thursday, September 18, 2008 02:22 AM Pacific Standard Time
Subject: Re: ephemerals handling after restart
thanks for your answer!
Is the session recoverable in case the zk server was restarted in
On Sep 12, 2008, at 3:52 PM, Benjamin Reed wrote:
> If a application does not close the ZooKeeper session before shutting
> down, ZooKeeper will not cleanup the session until it times out. So
> an application crashes and restarts, ZooKeeper doesn't know if the
> client is a restart of an old client or a new client.
> There is a way to alleviate this problem: you can actually maintain a
> session across client application restarts. If you save off the
> id and password, when you restart you can try to reconnect to the
> session using the ZooKeeper constructor that takes the old session id
> and password. If the reconnect is successful you can then close the
> session and get everything to clean up immediately. (Or you could keep
> using the recovered session if you want to.)
> -----Original Message-----
> From: Johannes Zillmann [mailto:[EMAIL PROTECTED]
> Sent: Friday, September 12, 2008 2:49 AM
> To: firstname.lastname@example.org
> Subject: ephemerals handling after restart
> Hi all,
> i have a question regarding ephemerals and it behavior on client
> We've a master/node cluster similar to a hadoop hdfs cluster but using
> zk for management.
> The nodes creates an ephemeral to announce there existence to the
> Now what i recognized is that after stopping the whole cluster and
> starting only the master again, still some ephemeral nodes may exists
> for some seconds.
> That leads me to following questions.
> What is if a node starts up again. Do it have to clean up it "old"
> ephemeral node, or can it somehow acquire the old one ?
> Just trying to find a best way how to deal with this, since on regular
> restart of the cluster i often recognize something like this
> master : node1, node2 connected
> master : node2 disconnected
> master : node2 connected again
> Thanks for any help
> 101tec GmbH
> Halle (Saale), Saxony-Anhalt, Germany
Halle (Saale), Saxony-Anhalt, Germany