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From Mahadev Konar <maha...@yahoo-inc.com>
Subject Re: znode cversion decreasing?
Date Mon, 12 Apr 2010 21:33:44 GMT
Hi Kevin,

 Thanks for the info. Could you cut and paste the code you are using that
prints the view info?
That would help. We can then create a jira and follow up on that.

Also, a zookeeper client can never go back in time (even if its gets
disconnected and connected back to another server).

Thanks
mahadev


On 4/12/10 2:26 PM, "Kevin Webb" <kcwebb@cs.ucsd.edu> wrote:

> On Mon, 12 Apr 2010 09:27:46 -0700
> Mahadev Konar <mahadev@yahoo-inc.com> wrote:
> 
>> 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
> 
> Thanks Mahadev and Patrick!
> 
> Here are some more details:
> 
> I'm using the C client and running three servers on PlanetLab, with
> each server on a different continent.  Most of the time, the cversion
> is increasing as expected.  I'm never deleting the group node, so
> that's not the issue.
> 
> Of course, now that I've emailed this list, I haven't seen it happen
> again...  
> 
> I do have one old log file though:
> 
> ZK(10): 1270514949 (Re)Connected to zookeeper server.
> ZK(10): 1270514952 Beginning new view #7.  Unsetting panic...
> GOSSIP(10): 1270514952 Changing view to 7
> ZK(10): 1270515798 Disconnected from zookeeper.  Setting panic...
> ZK(10): 1270515803 (Re)Connected to zookeeper server.
> ZK(10): 1270515806 Beginning new view #7.  Unsetting panic...
> GOSSIP(10): 1270515806 Ignoring delivery request for view 7, current
> view is 7.
> ZK(10): 1270516812 Disconnected from zookeeper.  Setting panic...
> ZK(10): 1270516823 (Re)Connected to zookeeper server.
> ZK(10): 1270516826 Beginning new view #11.  Unsetting panic...
> GOSSIP(10): 1270516826 Changing view to 11
> ZK(10): 1270519191 Disconnected from zookeeper.  Setting panic...
> ZK(10): 1270519195 (Re)Connected to zookeeper server.
> ZK(10): 1270519198 Beginning new view #9.  Unsetting panic...
> GOSSIP(10): 1270519198 Ignoring delivery request for view 9, current
> view is 11.
> 
> The large integral number is a Unix seconds-since-epoch timestamp (the
> result of calling time(NULL)).
> 
> In this case, the client connected, got group #7, disconnected,
> reconnected, got #7 again, disconnected, reconnected, got #11,
> disconnected, reconnected, and then got #9.
> 
> The host string that I pass to zookeeper_init contains only one
> address:port, so it's not an issue of re-connecting to a different
> server and getting old/stale information.
> 
> 
> If/when it does happen again, I'll be sure to also save the zookeeper
> server logs.
> 
> -Kevin


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