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From "Fournier, Camille F. [Tech]" <Camille.Fourn...@gs.com>
Subject RE: lost ZK events across datacenters
Date Wed, 01 Jun 2011 21:18:00 GMT
All clients are in different processes? 
I've used zkclient and haven't seen any problems, but I haven't hammered it too hard yet.
I took a long look at the code and didn't see any errors but there could always be something
very subtle.

-----Original Message-----
From: Jun Rao [mailto:junrao@gmail.com] 
Sent: Wednesday, June 01, 2011 4:09 PM
To: user@zookeeper.apache.org
Subject: Re: lost ZK events across datacenters

I am using the zkclient package (https://github.com/sgroschupf/zkclient.git).
The watcher code seems reasonable. Basically, each watcher event is first
added to a queue. A separate event thread dequeues each event and reads the
children of a path (which re-registers the watcher) and invokes the
registered listener.

Anybody knows any issues in zkclient?



On Wed, Jun 1, 2011 at 12:04 PM, Ted Dunning <ted.dunning@gmail.com> wrote:

> This is most commonly due, in my own history of programming errors, to
> writing code that has a race window in it.  It is conceivable that cross
> data-center operation would make such a race more of a problem.
> Can you say a bit about your code?  Did you make sure to use standard
> idioms
> as opposed to setting the watch in a different call from reading the data?
> On Wed, Jun 1, 2011 at 11:40 AM, Jun Rao <junrao@gmail.com> wrote:
> > Hi,
> >
> > I have a setup where multiple ZK clients are sitting in a different
> > datacenter from the ZK server. All clients registered the same child
> > watcher
> > on a path. However, when the children of the path changed, the watcher on
> 1
> > of the clients didn't fire. This seems to have happened a couple of times
> > to
> > me. I am using ZK 3.3.3. Has anyone used ZK in a cross datacenter setup
> and
> > seen problems like that before?
> >
> > Thanks,
> >
> > Jun
> >

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