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https://issues.apache.org/jira/browse/HDFS-13833?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16612968#comment-16612968
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Xiao Chen commented on HDFS-13833:
----------------------------------
Thanks all for the discussion / comments, and [~shwetayakkali] for the patch.
The approach looks good to me, some review comments:
- To address Kitti's comment #1, I think we can move the test case to
{{TestReplicationPolicy.java}}, if we do not want to create a new file.
{{TestReplicationPolicy}} is parameterized, but because this is a very quick
mock test I think that's ok.
- Instead of creating a mock BPPD object in the test, we can actually
instantiate a real one, using similar code from {{BlockPlacementPolicies}}.
This will get us less things to mock, and be able to call {{initialize}} on the
BPPD object.
{code}
final Class<? extends BlockPlacementPolicy> replicatorClass = conf
.getClass(DFSConfigKeys.DFS_BLOCK_REPLICATOR_CLASSNAME_KEY,
DFSConfigKeys.DFS_BLOCK_REPLICATOR_CLASSNAME_DEFAULT,
BlockPlacementPolicy.class);
replicationPolicy = ReflectionUtils.newInstance(replicatorClass, conf);
{code}
- Once the above is done, {{checkMaxLoad}} no longer needs the {{stats}} object
passed in.
- Suggest to cover a few other possibilities in the unit test. For example,
mock the stats and dndescriptor in a way that {{checkMaxLoad}} would return
false, and verify that with an assertion.
- Suggest to rename {{checkMaxLoad}} to a more self-explaining name.
{{excludeNodeByLoad}} or similar names will be more readable because reader
doesn't have to look into the logic to see what the return value means.
- Similar to above line, we can add a simple javadoc to the new method.
> Failed to choose from local rack (location = /default); the second replica is
> not found, retry choosing ramdomly
> ----------------------------------------------------------------------------------------------------------------
>
> Key: HDFS-13833
> URL: https://issues.apache.org/jira/browse/HDFS-13833
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Henrique Barros
> Assignee: Shweta
> Priority: Critical
> Attachments: HDFS-13833.001.patch
>
>
> I'm having a random problem with blocks replication with Hadoop
> 2.6.0-cdh5.15.0
> With Cloudera CDH-5.15.0-1.cdh5.15.0.p0.21
>
> In my case we are getting this error very randomly (after some hours) and
> with only one Datanode (for now, we are trying this cloudera cluster for a
> POC)
> Here is the Log.
> {code:java}
> Choosing random from 1 available nodes on node /default, scope=/default,
> excludedScope=null, excludeNodes=[]
> 2:38:20.527 PM DEBUG NetworkTopology
> Choosing random from 0 available nodes on node /default, scope=/default,
> excludedScope=null, excludeNodes=[192.168.220.53:50010]
> 2:38:20.527 PM DEBUG NetworkTopology
> chooseRandom returning null
> 2:38:20.527 PM DEBUG BlockPlacementPolicy
> [
> Node /default/192.168.220.53:50010 [
> Datanode 192.168.220.53:50010 is not chosen since the node is too busy
> (load: 8 > 0.0).
> 2:38:20.527 PM DEBUG NetworkTopology
> chooseRandom returning 192.168.220.53:50010
> 2:38:20.527 PM INFO BlockPlacementPolicy
> Not enough replicas was chosen. Reason:{NODE_TOO_BUSY=1}
> 2:38:20.527 PM DEBUG StateChange
> closeFile:
> /mobi.me/development/apps/flink/checkpoints/a5a6806866c1640660924ea1453cbe34/chk-2118/eef8bff6-75a9-43c1-ae93-4b1a9ca31ad9
> with 1 blocks is persisted to the file system
> 2:38:20.527 PM DEBUG StateChange
> *BLOCK* NameNode.addBlock: file
> /mobi.me/development/apps/flink/checkpoints/a5a6806866c1640660924ea1453cbe34/chk-2118/1cfe900d-6f45-4b55-baaa-73c02ace2660
> fileId=129628869 for DFSClient_NONMAPREDUCE_467616914_65
> 2:38:20.527 PM DEBUG BlockPlacementPolicy
> Failed to choose from local rack (location = /default); the second replica is
> not found, retry choosing ramdomly
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy$NotEnoughReplicasException:
>
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseRandom(BlockPlacementPolicyDefault.java:784)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseRandom(BlockPlacementPolicyDefault.java:694)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseLocalRack(BlockPlacementPolicyDefault.java:601)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseLocalStorage(BlockPlacementPolicyDefault.java:561)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTargetInOrder(BlockPlacementPolicyDefault.java:464)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:395)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:270)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:142)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseTarget(BlockPlacementPolicyDefault.java:158)
> at
> org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1715)
> at
> org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:3505)
> at
> org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:694)
> at
> org.apache.hadoop.hdfs.server.namenode.AuthorizationProviderProxyClientProtocol.addBlock(AuthorizationProviderProxyClientProtocol.java:219)
> at
> org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:507)
> at
> org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:617)
> at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:1073)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2281)
> at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2277)
> at java.security.AccessController.doPrivileged(Native Method)
> at javax.security.auth.Subject.doAs(Subject.java:422)
> at
> org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1920)
> at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2275)
> {code}
> This part makes no sense at all:
> {code:java}
> load: 8 > 0.0{code}
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