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https://issues.apache.org/jira/browse/HDFS-16907?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17684115#comment-17684115
]
ASF GitHub Bot commented on HDFS-16907:
---------------------------------------
virajjasani commented on code in PR #5349:
URL: https://github.com/apache/hadoop/pull/5349#discussion_r1096495331
##########
hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/DataNode.java:
##########
@@ -3832,7 +3837,38 @@ public boolean isDatanodeFullyStarted() {
}
return true;
}
-
+
+ /**
+ * Wait for the datanode to be fully started and also connected to active
namenode. This means
+ * wait until the given time duration for all the BP threads to come alive
and all the block
+ * pools to be initialized. Wait until any one of the BP service actor is
connected to active
+ * namenode.
+ *
+ * @param waitTimeMs Wait time in millis for this method to return the
datanode probes. If
+ * datanode stays unhealthy or not connected to any active namenode even
after the given wait
+ * time elapses, it returns false.
+ * @return true - if the data node is fully started and connected to active
namenode within
+ * the given time internal, false otherwise.
+ */
+ public boolean isDatanodeHealthy(long waitTimeMs) {
+ long startTime = monotonicNow();
+ while (monotonicNow() - startTime <= waitTimeMs) {
+ if (isDatanodeFullyStartedAndConnectedToActiveNN()) {
+ return true;
+ }
+ }
+ return false;
+ }
Review Comment:
I think it's fine, the client trying to probe could also have it's own time
based looping. Scripting can usually do that so we are good. Let me make this
change. Thanks
> Add LastHeartbeatResponseTime for BP service actor
> --------------------------------------------------
>
> 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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