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From Benjamin Reed <br...@yahoo-inc.com>
Subject RE: exist return true before event comes in
Date Tue, 04 Aug 2009 11:08:10 GMT
You will always have strict ordering of execution, but if you want to see the results in a
strict order you must use the async call.

ben

Sent from my phone.

-----Original Message-----
From: Stefan Groschupf <sg@101tec.com>
Sent: Monday, August 03, 2009 10:38 PM
To: zookeeper-user@hadoop.apache.org <zookeeper-user@hadoop.apache.org>
Subject: Re: exist return true before event comes in


Interesting, that basically means if I want strict order, I have to
use the async api?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Hadoop training and consulting
http://www.scaleunlimited.com
http://www.101tec.com



On Aug 3, 2009, at 8:10 PM, Benjamin Reed wrote:

> I assume you are calling the synchronous version of exists. The
> callbacks for both the watches and async calls are processed by a
> callback thread, so the ordering is strict. Synchronous call
> responses are not queued to the callback thread. (this allows you to
> make synchronous calls in callbacks without deadlocking.) thus the
> effect you are seeing may be due to a backed up callback queue and/
> or thread scheduling.
>
> ben
>
> Sent from my phone.
>
> -----Original Message-----
> From: Stefan Groschupf <sg@101tec.com>
> Sent: Monday, August 03, 2009 9:31 PM
> To: zookeeper-user@hadoop.apache.org <zookeeper-
> user@hadoop.apache.org>
> Subject: exist return true before event comes in
>
>
> Hi,
>
> I'm running into following problem writing a fasade for Zk Client (http://github.com/joa23/zkclient/
> )
>
> 1.) Subscribe a watch via exist(path, true) for a path.
> 2.) Create a persistent node.
> 3.) Call exist and it returns true
> 4.) Zookeeper sends a NodeCreated event.
>
>
> I would expect that the client would get the NodeCreated event before
> exist returns true.
> Does anyone has a idea of a pattern that secures that exist return
> false, before the event is triggered?
> Thanks,
> Stefan
>
>


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