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https://issues.apache.org/jira/browse/HDFS-10512?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15357631#comment-15357631
 ] 

Wei-Chiu Chuang commented on HDFS-10512:
----------------------------------------

Hi [~linyiqun] and [~xyao],
how do you think about this patch:

{noformat}
diff --git 
a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
 
b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
index d782e85..0b3738a 100644
--- 
a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
+++ 
b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java
@@ -1152,6 +1152,12 @@ public void reportBadBlocks(ExtendedBlock block) throws 
IOException{
         block, volume.getStorageID(), volume.getStorageType());
   }

+  public void reportBadBlocks(ExtendedBlock block, FsVolumeSpi volume ) throws 
IOException{
+    BPOfferService bpos = getBPOSForBlock(block);
+    bpos.reportBadBlocks(
+        block, volume.getStorageID(), volume.getStorageType());
+  }
+
   /**
    * Report a bad block on another DN (eg if we received a corrupt replica
    * from a remote host).
diff --git 
a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/VolumeScanner.java
 
b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/VolumeScanner.java
index d0dc9ed..7a9ecf2 100644
--- 
a/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/VolumeScanner.java
+++ 
b/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/VolumeScanner.java
@@ -283,7 +283,7 @@ public void handle(ExtendedBlock block, IOException e) {
       }
       LOG.warn("Reporting bad {} on {}", block, volume.getBasePath());
       try {
-        scanner.datanode.reportBadBlocks(block);
+        scanner.datanode.reportBadBlocks(block, volume);
       } catch (IOException ie) {
         // This is bad, but not bad enough to shut down the scanner.
         LOG.warn("Cannot report bad " + block.getBlockId(), e);

{noformat}

Thanks

> VolumeScanner may terminate due to NPE in DataNode.reportBadBlocks
> ------------------------------------------------------------------
>
>                 Key: HDFS-10512
>                 URL: https://issues.apache.org/jira/browse/HDFS-10512
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: datanode
>            Reporter: Wei-Chiu Chuang
>            Assignee: Yiqun Lin
>         Attachments: HDFS-10512.001.patch, HDFS-10512.002.patch
>
>
> VolumeScanner may terminate due to unexpected NullPointerException thrown in 
> {{DataNode.reportBadBlocks()}}. This is different from HDFS-8850/HDFS-9190
> I observed this bug in a production CDH 5.5.1 cluster and the same bug still 
> persist in upstream trunk.
> {noformat}
> 2016-04-07 20:30:53,830 WARN 
> org.apache.hadoop.hdfs.server.datanode.VolumeScanner: Reporting bad 
> BP-1800173197-10.204.68.5-1444425156296:blk_1170134484_96468685 on /dfs/dn
> 2016-04-07 20:30:53,831 ERROR 
> org.apache.hadoop.hdfs.server.datanode.VolumeScanner: VolumeScanner(/dfs/dn, 
> DS-89b72832-2a8c-48f3-8235-48e6c5eb5ab3) exiting because of exception
> java.lang.NullPointerException
>         at 
> org.apache.hadoop.hdfs.server.datanode.DataNode.reportBadBlocks(DataNode.java:1018)
>         at 
> org.apache.hadoop.hdfs.server.datanode.VolumeScanner$ScanResultHandler.handle(VolumeScanner.java:287)
>         at 
> org.apache.hadoop.hdfs.server.datanode.VolumeScanner.scanBlock(VolumeScanner.java:443)
>         at 
> org.apache.hadoop.hdfs.server.datanode.VolumeScanner.runLoop(VolumeScanner.java:547)
>         at 
> org.apache.hadoop.hdfs.server.datanode.VolumeScanner.run(VolumeScanner.java:621)
> 2016-04-07 20:30:53,832 INFO 
> org.apache.hadoop.hdfs.server.datanode.VolumeScanner: VolumeScanner(/dfs/dn, 
> DS-89b72832-2a8c-48f3-8235-48e6c5eb5ab3) exiting.
> {noformat}
> I think the NPE comes from the volume variable in the following code snippet. 
> Somehow the volume scanner know the volume, but the datanode can not lookup 
> the volume using the block.
> {code}
> public void reportBadBlocks(ExtendedBlock block) throws IOException{
>     BPOfferService bpos = getBPOSForBlock(block);
>     FsVolumeSpi volume = getFSDataset().getVolume(block);
>     bpos.reportBadBlocks(
>         block, volume.getStorageID(), volume.getStorageType());
>   }
> {code}



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