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Date: Sat, 10 Dec 2011 02:32:39 +0000 (UTC)
From: "Uma Maheswara Rao G (Commented) (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
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Subject: [jira] [Commented] (HDFS-2553) BlockPoolSliceScanner spinning in
 loop
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    [ https://issues.apache.org/jira/browse/HDFS-2553?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13166752#comment-13166752 ] 

Uma Maheswara Rao G commented on HDFS-2553:
-------------------------------------------

Hi Todd,

Thanks for the review!
Updated the patch!
changed to (!blockInfoSet.isEmpty() && !(this.isFirstBlockProcessed()))) {
Also retained the isEmpty condition in isFirstBlockProcessed because previous(above) check was not there in synchronization. So, there is a chance that block can be removed when just entering into isFirstBlockProcessed.

Thanks
Uma
                
> BlockPoolSliceScanner spinning in loop
> --------------------------------------
>
>                 Key: HDFS-2553
>                 URL: https://issues.apache.org/jira/browse/HDFS-2553
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: data-node
>    Affects Versions: 0.23.0, 0.24.0
>            Reporter: Todd Lipcon
>            Assignee: Uma Maheswara Rao G
>            Priority: Critical
>         Attachments: CPUUsage.jpg, HDFS-2553.patch, HDFS-2553.patch
>
>
> Playing with trunk, I managed to get a DataNode in a situation where the BlockPoolSliceScanner is spinning in the following loop, using 100% CPU:
>         at org.apache.hadoop.hdfs.server.datanode.DataNode$BPOfferService.isAlive(DataNode.java:820)
>         at org.apache.hadoop.hdfs.server.datanode.DataNode.isBPServiceAlive(DataNode.java:2962)
>         at org.apache.hadoop.hdfs.server.datanode.BlockPoolSliceScanner.scan(BlockPoolSliceScanner.java:625)
>         at org.apache.hadoop.hdfs.server.datanode.BlockPoolSliceScanner.scanBlockPoolSlice(BlockPoolSliceScanner.java:614)
>         at org.apache.hadoop.hdfs.server.datanode.DataBlockScanner.run(DataBlockScanner.java:95)

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