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https://issues.apache.org/jira/browse/HDFS-12749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16420758#comment-16420758
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Kihwal Lee commented on HDFS-12749:
-----------------------------------
The {{register()}} method is called from two different contexts. BP service
actor loop and command processing (through {{reRegister()}}). The quoted code
above is from the actor loop. In the {{catch}} block of {{processCommand()}},
you can add an equivalent logic.
{code}
boolean processCommand(DatanodeCommand[] cmds) {
if (cmds != null) {
for (DatanodeCommand cmd : cmds) {
try {
if (bpos.processCommandFromActor(cmd, this) == false) {
return false;
}
} catch(RemoteException re) {
String reClass = re.getClassName();
if (UnregisteredNodeException.class.getName().equals(reClass) ||
DisallowedDatanodeException.class.getName().equals(reClass) ||
IncorrectVersionException.class.getName().equals(reClass)) {
LOG.warn(this + " is shutting down", re);
shouldServiceRun = false;
return false;
}
} catch (IOException ioe) {
LOG.warn("Error processing datanode Command", ioe);
}
}
}
return true;
}
{code}
Your version of {{register()}} will retry on {{IOException}}, which includes
IPC timeout. If the NN explicitly throws a {{RemoteException}}, this will be
caught and rethrown in your updated {{register()}}. This will bubble up to
{{processCommand()}} above, which will stop the service actor if the condition
is terminal.
> 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-12749.001.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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