Yes Ben
-----Original Message----- From: Johannes Zillmann [mailto:[EMAIL PROTECTED] Sent: Thursday, September 18, 2008 02:22 AM Pacific Standard Time To: zookeeper-user@hadoop.apache.org Subject: Re: ephemerals handling after restart Hi Ben, thanks for your answer! Is the session recoverable in case the zk server was restarted in meantime ? Johannes 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 > when > 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 > session > 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.) > > ben > > -----Original Message----- > From: Johannes Zillmann [mailto:[EMAIL PROTECTED] > Sent: Friday, September 12, 2008 2:49 AM > To: zookeeper-user@hadoop.apache.org > Subject: ephemerals handling after restart > > Hi all, > > i have a question regarding ephemerals and it behavior on client > crash/ > restart. > 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 > master. > > 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 > Johannes > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > 101tec GmbH > Halle (Saale), Saxony-Anhalt, Germany > http://www.101tec.com > > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 101tec GmbH Halle (Saale), Saxony-Anhalt, Germany http://www.101tec.com
