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Zookeeper >> mail # user >> Implicit restriction of snapCount


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Implicit restriction of snapCount
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
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