Hadoop formatted HDFS error Java.net.UnknownHostException:localhost.localdomain:localhost.localdomain

Exception description

In the case of an unknown hostname when you format the Hadoop namenode-format command on HDFS, the exception information is as follows:

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2. [Email protected] bin]$ Hadoop Namenode-format
4. 11/06/22 07:33:31 INFO Namenode. Namenode:startup_msg:
6. /************************************************************
8. Startup_msg:starting NameNode
10. Startup_msg:host = Java.net.UnknownHostException:localhost.localdomain:localhost.localdomain
12. Startup_msg:args = [-format]
14. Startup_msg:version = 0.20.0
16. Startup_msg:build = Https://svn.apache.org/repos/asf/hadoop/core/branches/branch-0.20-r 763504; Compiled by ' Ndaley ' on Thu Apr 9 05:18:40 UTC 2009
18. ************************************************************/
20. Re-format filesystem In/tmp/hadoop/hadoop-shirdrn/dfs/name? (Y or N) Y
22. 11/06/22 07:33:36 INFO Namenode. Fsnamesystem:fsowner=shirdrn,shirdrn
24. 11/06/22 07:33:36 INFO Namenode. Fsnamesystem:supergroup=supergroup
26. 11/06/22 07:33:36 INFO Namenode. Fsnamesystem:ispermissionenabled=true
28. 11/06/22 07:33:36 INFO Metrics. Metricsutil:unable to obtain HostName
30. Java.net.UnknownHostException:localhost.localdomain:localhost.localdomain
32. At Java.net.InetAddress.getLocalHost (inetaddress.java:1353)
34. At Org.apache.hadoop.metrics.MetricsUtil.getHostName (metricsutil.java:91)
36. At Org.apache.hadoop.metrics.MetricsUtil.createRecord (metricsutil.java:80)
38. At Org.apache.hadoop.hdfs.server.namenode.FSDirectory.initialize (fsdirectory.java:73)
40. At Org.apache.hadoop.hdfs.server.namenode.fsdirectory.<init> (fsdirectory.java:68)
42. At Org.apache.hadoop.hdfs.server.namenode.fsnamesystem.<init> (fsnamesystem.java:370)
44. At Org.apache.hadoop.hdfs.server.namenode.NameNode.format (namenode.java:853)
46. At Org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode (namenode.java:947)
48. At Org.apache.hadoop.hdfs.server.namenode.NameNode.main (namenode.java:964)
50. 11/06/22 07:33:36 INFO Common. Storage:image file of size saved in 0 seconds.
52. 11/06/22 07:33:36 INFO Common. Storage:storage Directory/tmp/hadoop/hadoop-shirdrn/dfs/name has been successfully formatted.
54. 11/06/22 07:33:36 INFO Namenode. Namenode:shutdown_msg:
56. /************************************************************
58. Shutdown_msg:shutting down NameNode at Java.net.UnknownHostException:localhost.localdomain:localhost.localdomain
60. ************************************************************/

We can see by executing the hostname command:

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1. [Email protected] bin]# hostname
2. Localhost.localdomain

That is, Hadoop in the format of HDFs, the host name obtained through the hostname command is Localhost.localdomain, and then in the/etc/hosts file mapping, not found, look at my/etc/ Hosts content:

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1. [Email protected] bin]# cat/etc/hosts
2. # don't remove the following line, or various programs
3. # that require network functionality would fail.
4. 127.0.0.1 localhost localhost
5. 192.168.1.103 localhost localhost

Also said that through the localhost.localdomain can not be mapped to an IP address, so the error.

At this point, we look at the/etc/sysconfig/network file:

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1. Networking=yes
2. Networking_ipv6=yes
3. Hostname=localhost.localdomain

Visible, execute hostname Gets the value of the hostname configured here.

Workaround

Modify the value of hostname in/etc/sysconfig/network to localhost, or the host name that you specify, to ensure that localhost maps to the correct IP address in the/etc/hosts file, and then restart the Network service:

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1. [Email protected] bin]#/etc/rc.d/init.d/network restart
2. Shutting down interface eth0: [OK]
3. Shutting down loopback interface: [OK]
4. Bringing up loopback interface: [OK]
5. Bringing Up interface eth0:
6. Determining IP information for eth0 ... done.
7. [OK]

At this point, the format HDFs command is executed, and the HDFs cluster is started properly.

Formatting:

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2. [Email protected] bin]$ Hadoop Namenode-format
4. 11/06/22 08:02:37 INFO Namenode. Namenode:startup_msg:
6. /************************************************************
8. Startup_msg:starting NameNode
10. Startup_msg:host = localhost/127.0.0.1
12. Startup_msg:args = [-format]
14. Startup_msg:version = 0.20.0
16. Startup_msg:build = Https://svn.apache.org/repos/asf/hadoop/core/branches/branch-0.20-r 763504; Compiled by ' Ndaley ' on Thu Apr 9 05:18:40 UTC 2009
18. ************************************************************/
20. 11/06/22 08:02:37 INFO Namenode. Fsnamesystem:fsowner=shirdrn,shirdrn
22. 11/06/22 08:02:37 INFO Namenode. Fsnamesystem:supergroup=supergroup
24. 11/06/22 08:02:37 INFO Namenode. Fsnamesystem:ispermissionenabled=true
26. 11/06/22 08:02:37 INFO Common. Storage:image file of size saved in 0 seconds.
28. 11/06/22 08:02:37 INFO Common. Storage:storage Directory/tmp/hadoop/hadoop-shirdrn/dfs/name has been successfully formatted.
30. 11/06/22 08:02:37 INFO Namenode. Namenode:shutdown_msg:
32. /************************************************************
34. Shutdown_msg:shutting down NameNode at localhost/127.0.0.1
36. ************************************************************/

Start:

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2. [Email protected] bin]$ start-all.sh
4. Starting Namenode, logging to/home/shirdrn/eclipse/eclipse-3.5.2/hadoop/hadoop-0.20.0/logs/ Hadoop-shirdrn-namenode-localhost.out
6. Localhost:starting Datanode, logging to/home/shirdrn/eclipse/eclipse-3.5.2/hadoop/hadoop-0.20.0/logs/ Hadoop-shirdrn-datanode-localhost.out
8. Localhost:starting Secondarynamenode, logging to/home/shirdrn/eclipse/eclipse-3.5.2/hadoop/hadoop-0.20.0/logs/ Hadoop-shirdrn-secondarynamenode-localhost.out
10. Starting Jobtracker, logging to/home/shirdrn/eclipse/eclipse-3.5.2/hadoop/hadoop-0.20.0/logs/ Hadoop-shirdrn-jobtracker-localhost.out
12. Localhost:starting Tasktracker, logging to/home/shirdrn/eclipse/eclipse-3.5.2/hadoop/hadoop-0.20.0/logs/ Hadoop-shirdrn-tasktracker-localhost.out

View:

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1. [Email protected] bin]$ JPS
2. 8192 Tasktracker
3. 7905 DataNode
4. 7806 NameNode
5. 8065 Jobtracker
6. 8002 Secondarynamenode
7. 8234 Jps
8. From 6562292

Hadoop formatted HDFS error Java.net.UnknownHostException:localhost.localdomain:localhost.localdomain