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https://issues.apache.org/jira/browse/HDFS-16907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17684078#comment-17684078
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ASF GitHub Bot commented on HDFS-16907:
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slfan1989 commented on PR #5349:
URL: https://github.com/apache/hadoop/pull/5349#issuecomment-1416644855
Quick Look, LGTM.
> BP service actor LastHeartbeat is not sufficient to track realtime connection
> breaks
> ------------------------------------------------------------------------------------
>
> Key: HDFS-16907
> URL: https://issues.apache.org/jira/browse/HDFS-16907
> Project: Hadoop HDFS
> Issue Type: Improvement
> Reporter: Viraj Jasani
> Assignee: Viraj Jasani
> Priority: Major
> Labels: pull-request-available
> Attachments: Screenshot 2023-02-03 at 6.12.24 PM.png
>
>
> Each BP service actor thread maintains _lastHeartbeatTime_ with the namenode
> that it is connected to. However, this is updated even if the connection to
> the namenode is broken.
> Suppose, the actor thread keeps heartbeating to namenode and suddenly the
> socket connection is broken. When this happens, until specific time duration,
> the actor thread consistently keeps updating _lastHeartbeatTime_ before even
> initiating heartbeat connection with namenode. If connection cannot be
> established even after RPC retries are exhausted, then IOException is thrown.
> This means that heartbeat response has not been received from the namenode.
> In the loop, the actor thread keeps trying connecting for heartbeat and the
> last heartbeat stays close to 1/2s even though in reality there is no
> response being received from namenode.
>
> Sample Exception from the BP service actor thread, during which LastHeartbeat
> stays very low:
> {code:java}
> 2023-02-03 22:34:55,725 WARN [xyz:9000] datanode.DataNode - IOException in
> offerService
> java.io.EOFException: End of File Exception between local host is: "dn-0";
> destination host is: "nn-1":9000; : java.io.EOFException; For more details
> see: http://wiki.apache.org/hadoop/EOFException
> at sun.reflect.GeneratedConstructorAccessor34.newInstance(Unknown Source)
> at
> sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
> at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
> at org.apache.hadoop.net.NetUtils.wrapWithMessage(NetUtils.java:913)
> at org.apache.hadoop.net.NetUtils.wrapException(NetUtils.java:862)
> at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1553)
> at org.apache.hadoop.ipc.Client.call(Client.java:1495)
> at org.apache.hadoop.ipc.Client.call(Client.java:1392)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine2$Invoker.invoke(ProtobufRpcEngine2.java:242)
> at
> org.apache.hadoop.ipc.ProtobufRpcEngine2$Invoker.invoke(ProtobufRpcEngine2.java:129)
> at com.sun.proxy.$Proxy17.sendHeartbeat(Unknown Source)
> at
> org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB.sendHeartbeat(DatanodeProtocolClientSideTranslatorPB.java:168)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.sendHeartBeat(BPServiceActor.java:544)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.offerService(BPServiceActor.java:682)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:890)
> at java.lang.Thread.run(Thread.java:750)
> Caused by: java.io.EOFException
> at java.io.DataInputStream.readInt(DataInputStream.java:392)
> at org.apache.hadoop.ipc.Client$IpcStreams.readResponse(Client.java:1884)
> at
> org.apache.hadoop.ipc.Client$Connection.receiveRpcResponse(Client.java:1176)
> at org.apache.hadoop.ipc.Client$Connection.run(Client.java:1074) {code}
> Attaching screenshots of how last heartbeat value looks when the above error
> is consistently getting logged.
>
> Last heartbeat response time is important to initiate any auto-recovery from
> datanode. Hence, we should introduce LastHeartbeatResponseTime that only gets
> updated if the BP service actor thread was successfully able to retrieve
> response from namenode.
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