Details
Major Description
The server's main thread is "Listener at ${hostname}/9000", it is confused easily. We can see the main thread like below.
"Listener at ${hostname}/9000" #1 prio=5 os_prio=0 tid=0x00007f8068016000 nid=0x5c086 in Object.wait() [0x00007f806f1d4000] java.lang.Thread.State: WAITING (on object monitor) at java.lang.Object.wait(Native Method) - waiting on <0x00007f7552553010> (a org.apache.hadoop.ipc.ProtobufRpcEngine$Server) at java.lang.Object.wait(Object.java:502) at org.apache.hadoop.ipc.Server.join(Server.java:3449) - locked <0x00007f7552553010> (a org.apache.hadoop.ipc.ProtobufRpcEngine$Server) at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.join(NameNodeRpcServer.java:613) at org.apache.hadoop.hdfs.server.namenode.NameNode.join(NameNode.java:1014) at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1774)