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https://issues.apache.org/jira/browse/HDFS-8113?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14498553#comment-14498553
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Colin Patrick McCabe commented on HDFS-8113:
--------------------------------------------
There are already a bunch of places in the code where we check whether
BlockCollection is null before doing something with it. Example:
{code}
if (block instanceof BlockInfoContiguous) {
BlockCollection bc = ((BlockInfoContiguous) block).getBlockCollection();
String fileName = (bc == null) ? "[orphaned]" : bc.getName();
out.print(fileName + ": ");
}
{code}
also:
{code}
private int getReplication(Block block) {
final BlockCollection bc = blocksMap.getBlockCollection(block);
return bc == null? 0: bc.getBlockReplication();
}
{code}
I think that the majority of cases already have a check. My suggestion is just
that we extend this checking against null to all uses of the
BlockInfoContiguous structure's block collection.
If the problem is too difficult to reproduce with a {{MiniDFSCluster}}, perhaps
we can just do a unit test of the copy constructor itself.
As I said earlier, I don't understand the rationale for keeping blocks with no
associated INode out of the BlocksMap. It complicates the block report since
it requires us to check whether each block has an associated inode or not
before adding it to the BlocksMap. But if that change seems too ambitious for
this JIRA, we can deal with that later.
> NullPointerException in BlockInfoContiguous causes block report failure
> -----------------------------------------------------------------------
>
> Key: HDFS-8113
> URL: https://issues.apache.org/jira/browse/HDFS-8113
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: namenode
> Affects Versions: 2.6.0
> Reporter: Chengbing Liu
> Assignee: Chengbing Liu
> Attachments: HDFS-8113.patch
>
>
> The following copy constructor can throw NullPointerException if {{bc}} is
> null.
> {code}
> protected BlockInfoContiguous(BlockInfoContiguous from) {
> this(from, from.bc.getBlockReplication());
> this.bc = from.bc;
> }
> {code}
> We have observed that some DataNodes keeps failing doing block reports with
> NameNode. The stacktrace is as follows. Though we are not using the latest
> version, the problem still exists.
> {quote}
> 2015-03-08 19:28:13,442 WARN org.apache.hadoop.hdfs.server.datanode.DataNode:
> RemoteException in offerService
> org.apache.hadoop.ipc.RemoteException(java.lang.NullPointerException):
> java.lang.NullPointerException
> at org.apache.hadoop.hdfs.server.blockmanagement.BlockInfo.(BlockInfo.java:80)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager$BlockToMarkCorrupt.(BlockManager.java:1696)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.checkReplicaCorrupt(BlockManager.java:2185)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.processReportedBlock(BlockManager.java:2047)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.reportDiff(BlockManager.java:1950)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.processReport(BlockManager.java:1823)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.processReport(BlockManager.java:1750)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.blockReport(NameNodeRpcServer.java:1069)
> at
> org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolServerSideTranslatorPB.blockReport(DatanodeProtocolServerSideTranslatorPB.java:152)
> at
> org.apache.hadoop.hdfs.protocol.proto.DatanodeProtocolProtos$DatanodeProtocolService$2.callBlockingMethod(DatanodeProtocolProtos.java:26382)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:587)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1026)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2013)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2009)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:415)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1623)
> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2007)
> {quote}
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