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Zookeeper, mail # user - Implicit restriction of snapCount


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Takashi Ohnishi 2013-10-03, 10:16
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Re: Implicit restriction of snapCount
Patrick Hunt 2013-10-03, 16:11
Sounds reasonable. Please enter a jira where we can discuss the issue
and how to resolve. It would also be great if you are interested to
provide a patch!
https://issues.apache.org/jira/browse/ZOOKEEPER

Thanks!

Patrick

On Thu, Oct 3, 2013 at 3:16 AM, Takashi Ohnishi
<[EMAIL PROTECTED]> wrote:
> Hello.
>
> When I did testing ZooKeeper 3.4.5, I found an implicit and slight
> restriction of snapCount.
>
> If snapCount is set to 1, ZooKeeper Server can start but it fails with the
> below error:
>
> 2013-10-02 18:09:07,600 [myid:1] - ERROR
> [SyncThread:1:SyncRequestProcessor@151] - Severe unrecoverable error,
> exiting
> java.lang.IllegalArgumentException: n must be positive
>         at java.util.Random.nextInt(Random.java:300)
>         at
> org.apache.zookeeper.server.SyncRequestProcessor.run(SyncRequestProcessor.ja
> va:93)
>
> In source code,  it maybe be supposed that snapCount must be 2 or more:
>      91             // we do this in an attempt to ensure that not all of
> the servers
>      92             // in the ensemble take a snapshot at the same time
>      93             int randRoll = r.nextInt(snapCount/2);
>
> I think this supposition is not bad because snapCount = 1 is not realistic
> setting...
> But, it may be better to mention this restriction in documentation or add a
> validation in the source code.
> How about?
>
> Regards,
>
> ++++++++++++
> Takashi Ohnishi
>
>
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Takashi Ohnishi 2013-10-04, 01:24