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https://issues.apache.org/jira/browse/HDFS-12749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16484503#comment-16484503
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Kihwal Lee commented on HDFS-12749:
-----------------------------------
The patch looks good, but a test case would still be good. We can test whether
the exception handling in non-startup registration is working. That is not
directly testing the reported issue, but will check whether the new code is
working.
Here is what I think can be done.
- Setup up a mini dfs cluster with an include host file. Refresh/reload if
necessary
- Remove a datanode from the include file.
- Force re-registration of the datanode.
- In detailedRpc metrics, {{DisallowedDatanodeExceptionNumOps}} should not go
up. I.e. the BP actor thread should shutdown.
The existing behavior is that the BP actor thread retries forever despite the
exception. Your patch also fixes this issue by handling exceptions properly in
DNA_REGISTER command processing.
See various existing test cases such as
{{TestDatanodeRegistration#testForcedRegistration}} for hints. See test cases
using {{HostsFileWriter}} for examples of include host file and refreshing it.
Decommissioning tests use it.
> DN may not send block report to NN after NN restart
> ---------------------------------------------------
>
> Key: HDFS-12749
> URL: https://issues.apache.org/jira/browse/HDFS-12749
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: datanode
> Affects Versions: 2.7.1, 2.8.3, 2.7.5, 3.0.0, 2.9.1
> Reporter: TanYuxin
> Assignee: He Xiaoqiao
> Priority: Major
> Attachments: HDFS-12749-branch-2.7.002.patch,
> HDFS-12749-trunk.003.patch, HDFS-12749-trunk.004.patch, HDFS-12749.001.patch
>
>
> Now our cluster have thousands of DN, millions of files and blocks. When NN
> restart, NN's load is very high.
> After NN restart，DN will call BPServiceActor#reRegister method to register.
> But register RPC will get a IOException since NN is busy dealing with Block
> Report. The exception is caught at BPServiceActor#processCommand.
> Next is the caught IOException:
> {code:java}
> WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Error processing
> datanode Command
> java.io.IOException: Failed on local exception: java.io.IOException:
> java.net.SocketTimeoutException: 60000 millis timeout while waiting for
> channel to be ready for read. ch : java.nio.channels.SocketChannel[connected
> local=/DataNode_IP:Port remote=NameNode_Host/IP:Port]; Host Details : local
> host is: "DataNode_Host/Datanode_IP"; destination host is:
> "NameNode_Host":Port;
> at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:773)
> at org.apache.hadoop.ipc.Client.call(Client.java:1474)
> at org.apache.hadoop.ipc.Client.call(Client.java:1407)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:229)
> at com.sun.proxy.$Proxy13.registerDatanode(Unknown Source)
> at
> org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB.registerDatanode(DatanodeProtocolClientSideTranslatorPB.java:126)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.register(BPServiceActor.java:793)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.reRegister(BPServiceActor.java:926)
> at
> org.apache.hadoop.hdfs.server.datanode.BPOfferService.processCommandFromActor(BPOfferService.java:604)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.processCommand(BPServiceActor.java:898)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.offerService(BPServiceActor.java:711)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:864)
> at java.lang.Thread.run(Thread.java:745)
> {code}
> The un-catched IOException breaks BPServiceActor#register, and the Block
> Report can not be sent immediately.
> {code}
> /**
> * Register one bp with the corresponding NameNode
> * <p>
> * The bpDatanode needs to register with the namenode on startup in order
> * 1) to report which storage it is serving now and
> * 2) to receive a registrationID
> *
> * issued by the namenode to recognize registered datanodes.
> *
> * @param nsInfo current NamespaceInfo
> * @see FSNamesystem#registerDatanode(DatanodeRegistration)
> * @throws IOException
> */
> void register(NamespaceInfo nsInfo) throws IOException {
> // The handshake() phase loaded the block pool storage
> // off disk - so update the bpRegistration object from that info
> DatanodeRegistration newBpRegistration = bpos.createRegistration();
> LOG.info(this + " beginning handshake with NN");
> while (shouldRun()) {
> try {
> // Use returned registration from namenode with updated fields
> newBpRegistration = bpNamenode.registerDatanode(newBpRegistration);
> newBpRegistration.setNamespaceInfo(nsInfo);
> bpRegistration = newBpRegistration;
> break;
> } catch(EOFException e) { // namenode might have just restarted
> LOG.info("Problem connecting to server: " + nnAddr + " :"
> + e.getLocalizedMessage());
> sleepAndLogInterrupts(1000, "connecting to server");
> } catch(SocketTimeoutException e) { // namenode is busy
> LOG.info("Problem connecting to server: " + nnAddr);
> sleepAndLogInterrupts(1000, "connecting to server");
> }
> }
>
> LOG.info("Block pool " + this + " successfully registered with NN");
> bpos.registrationSucceeded(this, bpRegistration);
> // random short delay - helps scatter the BR from all DNs
> scheduler.scheduleBlockReport(dnConf.initialBlockReportDelay);
> }
> {code}
> But NameNode has processed registerDatanode successfully, so it won't ask DN
> to re-register again
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