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https://issues.apache.org/jira/browse/HBASE-435?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12567413#action_12567413
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Jim Kellerman commented on HBASE-435:
-------------------------------------
In MultiRegionTable.makeMultiRegionTable, it is possible to run out of retries
in the following loop and exit the loop with a null HRegion:
HRegion r = null;
for (int i = 0; i < 30; i++) {
hri = t.getRegionLocation(HConstants.EMPTY_START_ROW).getRegionInfo();
LOG.info("Region location: " + hri);
r = cluster.getRegionThreads().get(0).getRegionServer().
onlineRegions.get(hri.getRegionName());
if (r != null) {
break;
}
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
LOG.warn("Waiting on region to come online", e);
}
}
// Flush the cache
cluster.getRegionThreads().get(0).getRegionServer().getCacheFlushListener().
flushRequested(r);
If you fall out of the loop after 30 retries, r is null and so you get the NPE
from inside of flushRequested which is trying to do:
QueueEntry e = new QueueEntry(region, System.currentTimeMillis());
synchronized (flushQueue) {
if (flushQueue.contains(e)) {
QueueEntry.equals is based on the its hashCode which is computed by:
public int hashCode() {
return this.region.getRegionInfo().hashCode();
}
So if region is null, dereferencing it will generate the NPE
> TestTableMapReduce failed in HBase-Patch #15
> --------------------------------------------
>
> Key: HBASE-435
> URL: https://issues.apache.org/jira/browse/HBASE-435
> Project: Hadoop HBase
> Issue Type: Bug
> Components: test
> Affects Versions: 0.2.0
> Reporter: Jim Kellerman
>
> TestTableMapReduce failed in HBase-Patch #15 see:
> http://hudson.zones.apache.org/hudson/job/HBase-Patch/15/testReport/
> java.lang.NullPointerException
> at
> org.apache.hadoop.hbase.HRegionServer$QueueEntry.hashCode(HRegionServer.java:187)
> at
> org.apache.hadoop.hbase.HRegionServer$QueueEntry.equals(HRegionServer.java:181)
> at java.util.AbstractCollection.contains(AbstractCollection.java:101)
> at
> org.apache.hadoop.hbase.HRegionServer$Flusher.flushRequested(HRegionServer.java:494)
> at
> org.apache.hadoop.hbase.MultiRegionTable.makeMultiRegionTable(MultiRegionTable.java:107)
> at
> org.apache.hadoop.hbase.mapred.TestTableMapReduce.localTestMultiRegionTable(TestTableMapReduce.java:284)
> at
> org.apache.hadoop.hbase.mapred.TestTableMapReduce.testTableMapReduce(TestTableMapReduce.java:205)
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