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https://issues.apache.org/jira/browse/HDFS-12749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16364280#comment-16364280
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He Xiaoqiao commented on HDFS-12749:
------------------------------------
ping [~xkrogen]
I also had seen this problems in our big production cluster, and I think this
is a blocked issue.
The issue was original reported by my colleague [~tanyuxin] and we applied this
patch to our production cluster based branch-2.7, the problems as mentioned
above disappears.
I think the description of this ticket may lead to little ambiguity. I would
like to offer more information,
a) {{BPServiceActor#register}} only catch exception {{EOFException}} and
{{SocketTimeoutException}} (both are subclass of IOException) when register to
NameNode.
b) when the request pass to under {{RPC}} layer, {{Client#call}} (line 1448)
may throw many type exceptions, such as {{InterruptedIOException}},
{{IOException}}, etc. of course for different exception reasons.
c) Load of NameNode may very high during restarting process, especially in big
cluster. when datanode reregister to namenode at this time, {{RPC#Client}} may
throw IOException (not subclass of IOException) to {{BPServiceActor#register}}
as [~tanyuxin] describe above.
d) The IOException will be catch by {{BPServiceActor#processCommand}} and print
warn log {{`WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Error
processing datanode Command`}} but not reinit context of {{BlockPool}} when
reregister and continue run, so {{BlockReport}} will not be scheduled
immediately (when DataNode send {{BlockReport}} to restarting NameNode based on
the last {{BlockReport}} time.)
e) Actually, There are other subsequent problems besides NOT schedule
{{BlockReport}} immediately. Such as block token secret keys not update
correctly and client can not read {{Blocks}} from this DataNode even if hold
the correct BlockToken.
I have reviewed patch and one minor suggestion,
a) please rebase an active branch (such as branch-2.7) and offer new patch;
b) it will be better if add new UnitTest for this fix.
If I am wrong please correct me. [~tanyuxin]
> 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
> Affects Versions: 2.7.1
> Reporter: TanYuxin
> Priority: Major
> Attachments: 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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