I have embedded similar code into a number of programs, but I haven't published them.
You could take a look at hbase. I think it uses the single file technique. On Sat, Nov 26, 2011 at 2:33 AM, Jérémie BORDIER <jeremie.bord...@gmail.com>wrote: > Hello Ted, > > Can you point to a good implementation of that single file leadership > election method you're describing ? > > Thanks, > Jérémie > > On Sat, Nov 26, 2011 at 8:37 AM, Ted Dunning <ted.dunn...@gmail.com> > wrote: > > I think that the code also needs: > > > > * comments. You need to put some java docs in that say what the > different > > classes and methods are intended to do. External documentation is nice, > > but hardly sufficient. > > > > * global handling of disconnection and pausing of masters during a > > disconnect. > > > > * a description of how you think you are handling error conditions > > > > * tests that demonstrate that you handle error conditions > > > > I would also take issue with Jordan's suggestion for retry logic. With > > ephemeral sequential node, retries are very dangerous in certain corner > > failure modes. This is the primary reason that I prefer the single file > > leader election method. With a reasonable number of masters (the most > > common case) this is completely sufficient since the herd effect isn't a > > problem for such a small herd. > > > > On Fri, Nov 25, 2011 at 10:17 PM, Jordan Zimmerman > > <jzimmer...@netflix.com>wrote: > > > >> A few comments: > >> > >> * NodeMonitor.createRootIfNotExists() should catch NodeExists. In the > case > >> of multiple clients, this is a possibility. > >> > >> * I'd add a start method and create the ZooKeeper instance there. This > >> gives users a chance to set a listener so as to receive all messages. > >> > >> * All ZooKeeper operations should be in some kind of retry loop. The > >> client can lose connection to a given server but successfully reconnect > to > >> another one in the cluster. > >> > >> * When creating the Znode, it can succeed on the server but fail to > return > >> the result to the client. On a Disconnect/Session exception, you should > >> retry and then call getChildren and search for your node. > >> > >> -JZ > >> > >> On 11/25/11 2:45 AM, "Olivier Van Acker" <cyberroa...@gmail.com> wrote: > >> > >> >I've written a example app on how to do implement leadership election > in > >> >with zookeeper > >> >Is there anyone on the list who'd like to review my app and if it needs > >> >improvement or not? > >> > > >> >the app is on github: > >> >https://github.com/cyberroadie/zookeeper-leader > >> > > >> >and explained how it works on my blog: > >> > > >> > http://cyberroadie.wordpress.com/2011/11/24/implementing-leader-election-w > >> >ith-zookeeper/ > >> > > >> >Olivier > >> > >> > > > > > > -- > Jérémie 'ahFeel' BORDIER >
