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Zookeeper >> mail # user >> More sync questions


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Jordan Zimmerman 2011-11-11, 06:29
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Patrick Hunt 2011-11-23, 17:01
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Re: More sync questions
In the way I understood the question, Jordan seems to have observed  
that sync() is not affecting exists (correct me if I'm wrong, please).  
If that's the case, then I believe we have a bug.

-Flavio

On Nov 23, 2011, at 6:01 PM, Patrick Hunt wrote:

> On Thu, Nov 10, 2011 at 10:29 PM, Jordan Zimmerman
> <[EMAIL PROTECTED]> wrote:
>> A while back I asked about sync() and got responses that said it's  
>> only needed for reads (getData, getChildren). I was looking through  
>> the source and it appears that this does _not_ apply to exsists().  
>> Am I reading that correctly? i.e. will exists() always return an  
>> accurate (in terms of the leader) view of a node's metadata?
>
> No, sync applies to any read. We call it "slow read" in some cases
> because it forces the follower to get up to date with the leader.
>
> Keep in mind that any read from any server is never "accurate" at
> least in the sense that you likely mean it. e.g. the state of
> leadership may change btw the time the server responds to your exists
> call and the time it takes for TCP/OS to propagate the response to
> your client.
> http://en.wikipedia.org/wiki/Fallacies_of_Distributed_Computing
>
> Patrick

flavio
junqueira

research scientist

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Jordan Zimmerman 2011-11-23, 18:53
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Flavio Junqueira 2011-11-24, 13:54
NEW: Monitor These Apps!
elasticsearch, apache solr, apache hbase, hadoop, redis, casssandra, amazon cloudwatch, mysql, memcached, apache kafka, apache zookeeper, apache storm, ubuntu, centOS, red hat, debian, puppet labs, java, senseiDB