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Date: Sat, 26 Oct 2013 07:39:31 +0000 (UTC)
From: "Tsz Wo (Nicholas), SZE (JIRA)" <jira@apache.org>
To: hdfs-issues@hadoop.apache.org
Message-ID: <JIRA.12675588.1382655573358.6858.1382773171078@arcas>
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Subject: [jira] [Updated] (HDFS-5412) Fix NPEs in BlockManager and
 DirectoryScanner
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     [ https://issues.apache.org/jira/browse/HDFS-5412?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Tsz Wo (Nicholas), SZE updated HDFS-5412:
-----------------------------------------

    Hadoop Flags: Reviewed

+1 patch looks good.

> Fix NPEs in BlockManager and DirectoryScanner
> ---------------------------------------------
>
>                 Key: HDFS-5412
>                 URL: https://issues.apache.org/jira/browse/HDFS-5412
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>            Reporter: Arpit Agarwal
>            Assignee: Arpit Agarwal
>         Attachments: h5412.02.patch, h5412.03.patch
>
>
> The directory scanner periodically compiles a report of differences between the datanode's on-disk and in-memory state.
> The code to generate the reports is in {{DirectoryScanner#scan}} and {{DirectoryScanner#getDiskReport}}. It looks like the volume field in {{ScanInfo}} is not correctly initialized while compiling the diffs. This was not an issue before but now we depend on the volume information being present. The bug triggers the following NPE during a scan if a block is present in the Datanode's in-memory block map but missing on disk:
> {code}
> java.lang.NullPointerException
> 	at org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.checkAndUpdate(FsDatasetImpl.java:1404)
> 	at org.apache.hadoop.hdfs.server.datanode.DirectoryScanner.reconcile(DirectoryScanner.java:416)
> 	at org.apache.hadoop.hdfs.server.datanode.DirectoryScanner.run(DirectoryScanner.java:365)
> 	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:439)
> 	at java.util.concurrent.FutureTask$Sync.innerRunAndReset(FutureTask.java:317)
> 	at java.util.concurrent.FutureTask.runAndReset(FutureTask.java:150)
> 	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$101(ScheduledThreadPoolExecutor.java:98)
> 	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.runPeriodic(ScheduledThreadPoolExecutor.java:180)
> 	at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:204)
> 	at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
> 	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
> 	at java.lang.Thread.run(Thread.java:695)
> {code}
> Another NPE exposed in {{BlockManager#reportDiff}}
> {code}
> java.lang.NullPointerException: null
>         at java.util.TreeMap.getEntry(TreeMap.java:324)
>         at java.util.TreeMap.remove(TreeMap.java:580)
>         at java.util.TreeSet.remove(TreeSet.java:259)
>         at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.reportDiff(BlockManager.java:1836)
>         at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.processReport(BlockManager.java:1709)
>         at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.processReport(BlockManager.java:1637)
>         at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.blockReport(NameNodeRpcServer.java:978)
>         at org.apache.hadoop.
> {code}


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