[
https://issues.apache.org/jira/browse/HDFS-9958?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Kuhu Shukla updated HDFS-9958:
------------------------------
Attachment: HDFS-9958.003.patch
Thanks a lot for the helpful comments [~walter.k.su].
bq. btw, which is not related to this topic, I think
findAndMarkBlockAsCorrupt(..) shouldn't support adding blk to the map if the
storage is not found.
I agree, fixing that in v3 of the patch fixes the test in a way and is coherent
with the blocksMap and corruptReplicaMap being in sync. It now throws an
IOException if such a case is encountered.
bq. I think countNodes(blk) going thru all storages is unnecessary. Also I
think numMachines should only include NORMAL and READ_ONLY. So
createLocatedBlock(..) going thru all storages is unnecessary.
After thinking on this, I agree that failed storages should not count towards
any decision that countNodes() is responsible for (which are quite a few),
hence no change there.
Additionally, if the latest change makes sense then having {{numCorruptNodes}}
seems futile to me. This patch doesn't remove it just yet.
> BlockManager#createLocatedBlocks can throw NPE for corruptBlocks on failed
> storages.
> ------------------------------------------------------------------------------------
>
> Key: HDFS-9958
> URL: https://issues.apache.org/jira/browse/HDFS-9958
> Project: Hadoop HDFS
> Issue Type: Bug
> Affects Versions: 2.7.2
> Reporter: Kuhu Shukla
> Assignee: Kuhu Shukla
> Attachments: HDFS-9958-Test-v1.txt, HDFS-9958.001.patch,
> HDFS-9958.002.patch, HDFS-9958.003.patch
>
>
> In a scenario where the corrupt replica is on a failed storage, before it is
> taken out of blocksMap, there is a race which causes the creation of
> LocatedBlock on a {{machines}} array element that is not populated.
> Following is the root cause,
> {code}
> final int numCorruptNodes = countNodes(blk).corruptReplicas();
> {code}
> countNodes only looks at nodes with storage state as NORMAL, which in the
> case where corrupt replica is on failed storage will amount to
> numCorruptNodes being zero.
> {code}
> final int numNodes = blocksMap.numNodes(blk);
> {code}
> However, numNodes will count all nodes/storages irrespective of the state of
> the storage. Therefore numMachines will include such (failed) nodes. The
> assert would fail only if the system is enabled to catch Assertion errors,
> otherwise it goes ahead and tries to create LocatedBlock object for that is
> not put in the {{machines}} array.
> Here is the stack trace:
> {code}
> java.lang.NullPointerException
> at
> org.apache.hadoop.hdfs.server.blockmanagement.DatanodeStorageInfo.toDatanodeInfos(DatanodeStorageInfo.java:45)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.DatanodeStorageInfo.toDatanodeInfos(DatanodeStorageInfo.java:40)
> at
> org.apache.hadoop.hdfs.protocol.LocatedBlock.<init>(LocatedBlock.java:84)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.createLocatedBlock(BlockManager.java:878)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.createLocatedBlock(BlockManager.java:826)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.createLocatedBlockList(BlockManager.java:799)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.createLocatedBlocks(BlockManager.java:899)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getBlockLocationsInt(FSNamesystem.java:1849)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getBlockLocations(FSNamesystem.java:1799)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getBlockLocations(FSNamesystem.java:1712)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.getBlockLocations(NameNodeRpcServer.java:588)
> at
> org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.getBlockLocations(ClientNamenodeProtocolServerSideTranslatorPB.java:365)
> at
> org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:616)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:982)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2049)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2045)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:415)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1657)
> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2043)
> {code}
--
This message was sent by Atlassian JIRA
(v6.3.4#6332)
