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From Mahadev Konar <maha...@yahoo-inc.com>
Subject Re: znode cversion decreasing?
Date Mon, 12 Apr 2010 16:27:46 GMT
HI Kevin,

 The cversion should be monotonically increasing for the the znode. It would
be a bug if its not. Can you please elaborate in which cases you are seeing
the cversion decreasing? If you can reproduce with an example that would be
great.

Thanks
mahadev


On 4/11/10 3:53 PM, "Kevin Webb" <kcwebb@cs.ucsd.edu> wrote:

> I'm using Zookeeper (3.2.2) for  a simple group membership service in
> the manner that is typically described[1,2]:
> 
> I create a znode for the group, and each present group member adds an
> ephemeral node under the group node.  I'm using the cversion of the
> group node as a "group number". I expected this value to be
> monotonically increasing, but I'm seeing instances where this isn't
> the case.  According to the programmer's guide, changes to a node will
> cause the appropriate version number to increase, but it says nothing
> about decreasing.
> 
> Am I misunderstanding something about the way node version numbers
> work?  Is there a better/recommended way to implement a monotonically
> increasing group number?
> 
> Thanks!
> Kevin
> 
> 
> [1] http://hadoop.apache.org/zookeeper/docs/r3.2.2/recipes.html
> [2] http://eng.kaching.com/2010/01/actually-implementing-group-management.html


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