本来下想在一台虚拟机上,搭建一个hadoop的测试hadoop,用于调试和阅读hadoop源代码,发现在虚拟机上执行:
$hostname -i
hostname: Unknown host
这个是因为没有设置/etc/hosts文件导致的,如果linux的环境是这样的,那么将会在启动datanode和tasktracker的时候失败,
datanode和namenode将会抛出如下的异常:
2015-01-28 12:36:36,506 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties 2015-01-28 12:36:36,535 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source MetricsSystem,sub=Stats registered. 2015-01-28 12:36:36,540 ERROR org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Error getting localhost name. Using ‘localhost‘... java.net.UnknownHostException: PC_PAT1: PC_PAT1: Name or service not known at java.net.InetAddress.getLocalHost(InetAddress.java:1473) at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.getHostname(MetricsSystemImpl.java:463) at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.configureSystem(MetricsSystemImpl.java:394) at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.configure(MetricsSystemImpl.java:390) at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.start(MetricsSystemImpl.java:152) at org.apache.hadoop.metrics2.impl.MetricsSystemImpl.init(MetricsSystemImpl.java:133) at org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.init(DefaultMetricsSystem.java:40) at org.apache.hadoop.metrics2.lib.DefaultMetricsSystem.initialize(DefaultMetricsSystem.java:50) at org.apache.hadoop.hdfs.server.datanode.DataNode.instantiateDataNode(DataNode.java:1520) at org.apache.hadoop.hdfs.server.datanode.DataNode.createDataNode(DataNode.java:1539) at org.apache.hadoop.hdfs.server.datanode.DataNode.secureMain(DataNode.java:1665) at org.apache.hadoop.hdfs.server.datanode.DataNode.main(DataNode.java:1682) Caused by: java.net.UnknownHostException: PC_PAT1: Name or service not known at java.net.Inet6AddressImpl.lookupAllHostAddr(Native Method) at java.net.InetAddress$1.lookupAllHostAddr(InetAddress.java:901) at java.net.InetAddress.getAddressesFromNameService(InetAddress.java:1293) at java.net.InetAddress.getLocalHost(InetAddress.java:1469) ... 11 more
解决方案是在/etc/hosts文件中添加如下红色的内容,即172.18.140.24 PC_PAT1
[email protected]_PAT1:~/hadoop-1.0.3> less /etc/hosts # # hosts This file describes a number of hostname-to-address # mappings for the TCP/IP subsystem. It is mostly # used at boot time, when no name servers are running. # On small systems, this file can be used instead of a # "named" name server. # Syntax: # # IP-Address Full-Qualified-Hostname Short-Hostname # #127.0.0.1 localhost #127.0.0.1 localhost.localdomain localhost cpyftest-2 127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 172.18.140.24 PC_PAT1 # special IPv6 addresses ::1 localhost ipv6-localhost ipv6-loopback fe00::0 ipv6-localnet ff00::0 ipv6-mcastprefix ff02::1 ipv6-allnodes ff02::2 ipv6-allrouters ff02::3 ipv6-allhosts
添加后,hostname –i 将会得到正确的结果:
将hostname unkown的问题解决后,重启hadoop集群,可以发现,datanode/tasktracker , namenode/jobtracker都启动了:
时间: 2024-08-04 07:47:52