【hadoop】DataNode,NameNode,JobTracker,TaskTracker用jps查看无法启动解决办法

start-all.sh和jps后出现一下问题

[code]
root@ubuntu:/opt/hadoop-0.20.2/bin# sh start-all.sh
starting namenode, logging to /opt/hadoop-0.20.2/bin/../logs/hadoop-root-namenode-ubuntu.out
localhost: starting datanode, logging to /opt/hadoop-0.20.2/bin/../logs/hadoop-root-datanode-ubuntu.out
localhost: starting secondarynamenode, logging to /opt/hadoop-0.20.2/bin/../logs/hadoop-root-secondarynamenode-ubuntu.out
localhost: Exception in thread "main" java.net.BindException: Address already in use
localhost:  at sun.nio.ch.Net.bind0(Native Method)
localhost:  at sun.nio.ch.Net.bind(Net.java:444)
localhost:  at sun.nio.ch.Net.bind(Net.java:436)
localhost:  at sun.nio.ch.ServerSocketChannelImpl.bind(ServerSocketChannelImpl.java:214)
localhost:  at sun.nio.ch.ServerSocketAdaptor.bind(ServerSocketAdaptor.java:74)
localhost:  at org.mortbay.jetty.nio.SelectChannelConnector.open(SelectChannelConnector.java:216)
localhost:  at org.apache.hadoop.http.HttpServer.start(HttpServer.java:425)
localhost:  at org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.initialize(SecondaryNameNode.java:165)
localhost:  at org.apache.hadoop.hdfs.server.namenode.SecondaryNameNode.<init>(SecondaryNameNode.java:115)
starting jobtracker, logging to /opt/hadoop-0.20.2/bin/../logs/hadoop-root-jobtracker-ubuntu.out
localhost: starting tasktracker, logging to /opt/hadoop-0.20.2/bin/../logs/hadoop-root-tasktracker-ubuntu.out
root@ubuntu:/opt/hadoop-0.20.2/bin# jps
45103 Jps
44501 NameNode
39024 -- process information unavailable

“Exception in thread “main” java.net.BindException: Address already in use”这个是端口占用问题

有前辈给我指出一道路：**先从日志中找是哪个端口被占用了

然后在“netstat -anp”查看是哪个进程占用了该端口，kill掉应该就可以了**

自己的解决办法：首先了解一下内容，DataNode,NameNode,JobTracker,TaskTracker各个端口号

Hadoop的常用WEB端口

Hadoop对外提供了可供访问的http server，开放了很多端口，下面介绍常用的几个端口:

50070端口

查看NameNode状态;

该端口的定义位于core-default.xml中，可以在core-site.xml中修改;

如果通过该端口看着这个页面，以为着NameNode节点是存活的。

50075端口

查看DataNode;

该地址和端口的定义位于hdfs-default.xml中，可以在hdfs-site.xml中修改。

50090端口

查看SecondaryNameNode。

50030端口

查看JobTracker状态的；

该端口定义在mapred-default.xml中，可以在mapred-site.xml中修改。

50060端口

查看TaskTracker

该端口定义位于mapred-default.xml，可以在mapred-site.xml中修改。

其次，用一下命令解决：

[code]root@ubuntu:~# lsof -i:50090
COMMAND   PID USER   FD   TYPE DEVICE SIZE/OFF NODE NAME
java    16073 root   52u  IPv6  74371      0t0  TCP *:50090 (LISTEN)
root@ubuntu:~# kill -9 16073

这样就kill掉了这个进程，端口占用问题解决了。重新start-all.sh，jps后就有DataNode,NameNode,JobTracker,TaskTracker