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Posted to common-dev@hadoop.apache.org by "dhruba borthakur (JIRA)" <ji...@apache.org> on 2007/03/08 20:04:24 UTC
[jira] Commented: (HADOOP-1092) NullPointerException in
HeartbeatMonitor thread
[ https://issues.apache.org/jira/browse/HADOOP-1092?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#action_12479411 ]
dhruba borthakur commented on HADOOP-1092:
------------------------------------------
A Datanode times-out and is declared dead by the Namenode. The Namenode invokes removeDatanode. This Datanode has a block that has only one replica.
Inside removeStoredBlock(), we remove this block from the blocksMap and then call neededReplication. update(block, -1, 0). Inside update(), we call blocksMap.get() and we fail to find the block becaase we have just removed it. Hence the null-pointer exception.
> NullPointerException in HeartbeatMonitor thread
> -----------------------------------------------
>
> Key: HADOOP-1092
> URL: https://issues.apache.org/jira/browse/HADOOP-1092
> Project: Hadoop
> Issue Type: Bug
> Components: dfs
> Affects Versions: 0.12.0
> Reporter: Nigel Daley
> Priority: Blocker
> Fix For: 0.12.1
>
>
> Running NNBench with latest trunk, I saw this NPE in the Namenode log:
> Exception in thread "org.apache.hadoop.dfs.FSNamesystem$HeartbeatMonitor@182bcde" java.lang.NullPointerException
> at org.apache.hadoop.dfs.FSNamesystem.countContainingNodes(FSNamesystem.java:2506)
> at org.apache.hadoop.dfs.FSNamesystem.access$000(FSNamesystem.java:52)
> at org.apache.hadoop.dfs.FSNamesystem$UnderReplicationBlocks.update(FSNamesystem.java:456)
> at org.apache.hadoop.dfs.FSNamesystem.removeStoredBlock(FSNamesystem.java:2242)
> at org.apache.hadoop.dfs.FSNamesystem.removeDatanode(FSNamesystem.java:1876)
> at org.apache.hadoop.dfs.FSNamesystem.heartbeatCheck(FSNamesystem.java:1958)
> at org.apache.hadoop.dfs.FSNamesystem$HeartbeatMonitor.run(FSNamesystem.java:1698)
> at java.lang.Thread.run(Thread.java:619)
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