[ 
https://issues.apache.org/jira/browse/HDFS-16907?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
 ]

Viraj Jasani updated HDFS-16907:
--------------------------------
    Description: 
BP service actor LastHeartbeat is not sufficient to track realtime connection 
breaks.

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.

  was:
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.


> 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
>
>
> BP service actor LastHeartbeat is not sufficient to track realtime connection 
> breaks.
> 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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