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https://issues.apache.org/jira/browse/HBASE-7871?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13612966#comment-13612966
]
Ted Yu commented on HBASE-7871:
-------------------------------
>From
>http://javasourcecode.org/html/open-source/jdk/jdk-6u23/java.util/TreeMap.java.html
> :
{code}
/** From CLR */
private void rotateLeft(Entry<K,V> p) {
if (p != null) {
Entry<K,V> r = p.right;
p.right = r.left;
if (r.left != null)
r.left.parent = p;
r.parent = p.parent;
if (p.parent == null)
root = r;
else if (p.parent.left == p)
p.parent.left = r;
else
p.parent.right = r;
r.left = p;
p.parent = r;
}
}
{code}
where line 2038 is:
{code}
p.right = r.left;
{code}
where p.right gets assigned null at line 2142 in deleteEntry():
{code}
p.left = p.right = p.parent = null;
{code}
This means that concurrent deregister() resulted in the NPE.
See Anoop's comment @ 22/Mar/13 12:34 above for more background.
> HBase can be stuck in the shutdown
> ----------------------------------
>
> Key: HBASE-7871
> URL: https://issues.apache.org/jira/browse/HBASE-7871
> Project: HBase
> Issue Type: Bug
> Components: master
> Affects Versions: 0.96.0
> Reporter: Nicolas Liochon
> Assignee: Ted Yu
> Priority: Critical
> Attachments: 7871.patch, 7871-v2.patch, s1.txt, TestStartStop.java
>
>
> The attached test fails ~1% of the the time on 0.96. It seems it does not
> fail on 0.94.5. It's simple: a table creation and some puts.
> I attach the stack. Logs says nothing it seems.
> The suspicious part is:
> {noformat}
> "RS_CLOSE_REGION-localhost,57575,1361197489166-2" prio=10
> tid=0x00007fb0c8775800 nid=0x61ac runnable [0x00007fb09f272000]
> java.lang.Thread.State: RUNNABLE
> at java.util.TreeMap.fixAfterDeletion(TreeMap.java:2193)
> at java.util.TreeMap.deleteEntry(TreeMap.java:2151)
> at java.util.TreeMap.remove(TreeMap.java:585)
> at java.util.TreeSet.remove(TreeSet.java:259)
> at
> org.apache.hadoop.hbase.regionserver.MetricsRegionAggregateSourceImpl.deregister(MetricsRegionAggregateSourceImpl.java:55)
> at
> org.apache.hadoop.hbase.regionserver.MetricsRegionSourceImpl.close(MetricsRegionSourceImpl.java:86)
> at
> org.apache.hadoop.hbase.regionserver.MetricsRegion.close(MetricsRegion.java:40)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.doClose(HRegion.java:1063)
> at
> org.apache.hadoop.hbase.regionserver.HRegion.close(HRegion.java:969)
> - locked <0x00000006944e2558> (a java.lang.Object)
> at
> org.apache.hadoop.hbase.regionserver.handler.CloseRegionHandler.process(CloseRegionHandler.java:146)
> at
> org.apache.hadoop.hbase.executor.EventHandler.run(EventHandler.java:203)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
> at
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
> at java.lang.Thread.run(Thread.java:662)
> {noformat}
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