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Posted to common-dev@hadoop.apache.org by "dhruba borthakur (JIRA)" <ji...@apache.org> on 2007/05/02 01:22:15 UTC
[jira] Commented: (HADOOP-1312) heartbeat monitor thread goes away
[ https://issues.apache.org/jira/browse/HADOOP-1312?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12492980 ]
dhruba borthakur commented on HADOOP-1312:
------------------------------------------
namenode .out file.
Exception in thread
"org.apache.hadoop.dfs.FSNamesystem$HeartbeatMonitor@5b9d2de4" java.util.ConcurrentModificationException
at
java.util.AbstractList$Itr.checkForComodification(AbstractList.java:372)
at java.util.AbstractList$Itr.next(AbstractList.java:343)
at
org.apache.hadoop.dfs.FSNamesystem.heartbeatCheck(FSNamesystem.java:1933)
at
org.apache.hadoop.dfs.FSNamesystem$HeartbeatMonitor.run(FSNamesystem.java:1697)
at java.lang.Thread.run(Thread.java:619)
> heartbeat monitor thread goes away
> ----------------------------------
>
> Key: HADOOP-1312
> URL: https://issues.apache.org/jira/browse/HADOOP-1312
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Reporter: dhruba borthakur
>
> The heartbeat monitor thread encounters a ConcurrentModificationException while iterating over the "heartbeats" data structure. This occurs when the namenode was getting restarted. There are actuallt two bugs here:
> 1. The Heartbeat Monitor thread needs to catch Exceptions and continue, instead of exiting.
> 2. The heartbeats data structures is protected by the heartbeats lock. The registerDatanode() method invokes removeDatanode() without acquiring the heartbeats monitor lock. This causes the ConcurrentModificationException.
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