[jira] [Created] (HBASE-8374) NPE when launching the balance

["Nicolas Liochon (JIRA)" <ji...@apache.org>]

Nicolas Liochon created HBASE-8374:
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             Summary: NPE when launching the balance
                 Key: HBASE-8374
                 URL: https://issues.apache.org/jira/browse/HBASE-8374
             Project: HBase
          Issue Type: Bug
          Components: Balancer
    Affects Versions: 0.95.0
         Environment: AWS / real cluster with 3 nodes + master
            Reporter: Nicolas Liochon


I don't reproduce this all the time, but I had it on a fairly clean env.
It occurs every 5 minutes (i.e. the balancer period). Impact is severe: the balancer does not run. When it starts to occurs, it occurs all the time. I haven't tried to restart the master, but I think it should be enough.
Now, looking at the code, the NPE is strange. 

{noformat}
2013-04-18 08:09:52,079 ERROR [box,60000,1366281581983-BalancerChore] org.apache.hadoop.hbase.master.balancer.BalancerChore: Caught exception
java.lang.NullPointerException
	at org.apache.hadoop.hbase.master.balancer.BaseLoadBalancer$Cluster.<init>(BaseLoadBalancer.java:145)
	at org.apache.hadoop.hbase.master.balancer.StochasticLoadBalancer.balanceCluster(StochasticLoadBalancer.java:194)
	at org.apache.hadoop.hbase.master.HMaster.balance(HMaster.java:1295)
	at org.apache.hadoop.hbase.master.balancer.BalancerChore.chore(BalancerChore.java:48)
	at org.apache.hadoop.hbase.Chore.run(Chore.java:81)
	at java.lang.Thread.run(Thread.java:662)
2013-04-18 08:09:52,103 DEBUG [box,60000,1366281581983-CatalogJanitor] org.apache.hadoop.hbase.client.ClientScanner: Creating scanner over .META. starting at key ''
{noformat}

{code}
          if (regionFinder != null) {
            //region location
            List<ServerName> loc = regionFinder.getTopBlockLocations(region);
            regionLocations[regionIndex] = new int[loc.size()];
            for (int i=0; i < loc.size(); i++) {
              regionLocations[regionIndex][i] = serversToIndex.get(loc.get(i));  // <========= NPE here
            }
          }
{code}


pinging [~enis], just in case.

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