ms209495 2013-11-26, 08:54
Camille Fournier 2013-11-26, 20:10
ms209495 2013-11-26, 22:28
Cameron McKenzie 2013-11-26, 22:34
Alexander Shraer 2013-11-26, 22:58
This is not necessarily true. The old master may not have an accurate
The ascending id idea that Alex mentions is a very nice way to put more
guarantees on the process.
On Tue, Nov 26, 2013 at 2:58 PM, Alexander Shraer <[EMAIL PROTECTED]> wrote:
> Cameron's solution basically relies on additional timing assumptions
> as Maciej mentions in his question.
> One more thing you could do is to implement increasing generation ids
> for masters, and have clients in your system reject commands from a
> master if they already know that a master with a higher generation id
> was elected (either because they saw a command from the new master or
> because they got a notification from ZK). This way each client can
> only have a single master and goes forward in time.
> On Tue, Nov 26, 2013 at 2:34 PM, Cameron McKenzie
> <[EMAIL PROTECTED]> wrote:
> > If I'm understanding your question correctly, you're worried that when
> > current 'master' loses its connection to ZooKeeper, a new 'master' will
> > elected and you will have 2 'master' nodes at the same time. As soon as
> > lose a connection to ZooKeeper there are no guarantees about any of the
> > state that you're determining from it. When you lose the ZooKeeper
> > connection, your 'master' must assume that it is no longer a 'master'
> > until it reconnects to ZooKeeper, at which point it will be able to work
> > out what's going on.
> > If you look at Apache Curator, its implementation of the Leader latch
> > recipe handles this loss of connection and reestablishment.
> > cheers
> > Cam
> > On Wed, Nov 27, 2013 at 9:28 AM, ms209495 <[EMAIL PROTECTED]> wrote:
> >> Thanks for the reply. I want to clarify one thing.
> >> I think about a System of 20 nodes, that uses ZooKeeper of 3 nodes.
> >> I think about master election among these 20 nodes, that do not run
> >> consensus, but they use zookeeper service for master election.
> >> I used 'leader' term for a leeder in Zookeeper (among 3 nodes), and
> >> 'master'
> >> term for master in the System (20 nodes).
> >> Solution is described here:
> >> http://zookeeper.apache.org/doc/trunk/recipes.html#sc_leaderElection (I
> >> would name it 'master' election, not 'leader' election), but I doubt if
> >> works reliable without additional timing assumptions as I described in
> >> previous post.
> >> Please consider my previous post in the context of the System that uses
> >> Zookeeper (not ZooKeeper itself).
> >> --
> >> View this message in context:
> >> Sent from the zookeeper-user mailing list archive at Nabble.com.
Cameron McKenzie 2013-11-27, 00:57
Alexander Shraer 2013-11-27, 01:20
Ted Dunning 2013-11-28, 05:14
Maciej 2013-11-26, 23:17
Cameron McKenzie 2013-11-26, 23:41
Bryan Thompson 2013-11-26, 23:27
Ivan Kelly 2013-11-28, 18:04