[Hadoop] problem record: filesystemapi reads HDFS data: info IPC. Client: retrying connect to server: localhost/127.0.0.1

[Problem]

When this code is used to read data on HDFS

public static void main(String[] args) throws Exception { String uri = args[0]; Configuration conf = new Configuration(); FileSystem fs = FileSystem.get(URI.create(uri),conf); InputStream in = null; try{ in = fs.open(new Path(uri)); IOUtils.copyBytes(in, System.out, 4096,false); }finally{ IOUtils.closeStream(in); }}

Error:

Ubuntu @ snda:/data/soft/hadoop-0.20.203.0 $ bin/hadoop jar ~ /Desktop/filesystemcat. Jar HDFS: // localhost/user/Ubuntu/output/part-00000
11/08/04 09:12:10 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 0 time (s ).
11/08/04 09:12:11 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 1 time (s ).
11/08/04 09:12:12 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 2 time (s ).
11/08/04 09:12:13 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 3 time (s ).
11/08/04 09:12:14 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 4 time (s ).
11/08/04 09:12:15 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 5 time (s ).
11/08/04 09:12:16 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 6 time (s ).
11/08/04 09:12:17 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 7 time (s ).
11/08/04 09:12:18 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 8 time (s ).
11/08/04 09:12:19 info IPC. Client: retrying connect to server: localhost/127.0.0.1: 8020. Already tried 9 time (s ).
Exception in thread "Main" Java. Lang. Reflect. invocationtargetexception
At sun. Reflect. nativemethodaccessorimpl. invoke0 (native method)
At sun. Reflect. nativemethodaccessorimpl. Invoke (nativemethodaccessorimpl. Java: 39)
At sun. Reflect. delegatingmethodaccessorimpl. Invoke (delegatingmethodaccessorimpl. Java: 25)
At java. Lang. Reflect. method. Invoke (method. Java: 597)
At org. Eclipse. jdt. Internal. jarinjarloader. jarrsrcloader. Main (jarrsrcloader. Java: 58)
At sun. Reflect. nativemethodaccessorimpl. invoke0 (native method)
At sun. Reflect. nativemethodaccessorimpl. Invoke (nativemethodaccessorimpl. Java: 39)
At sun. Reflect. delegatingmethodaccessorimpl. Invoke (delegatingmethodaccessorimpl. Java: 25)
At java. Lang. Reflect. method. Invoke (method. Java: 597)
At org. Apache. hadoop. util. runjar. Main (runjar. Java: 156)
Caused by: java.net. connectexception: Call to localhost/127.0.0.1: 8020 failed on connection exception: java.net. connectexception: Connection refused
At org. Apache. hadoop. IPC. Client. wrapexception (client. Java: 1057)
At org. Apache. hadoop. IPC. Client. Call (client. Java: 1033)
At org. Apache. hadoop. IPC. RPC $ invoker. Invoke (rpc. Java: 224)
At $ proxy1.getprotocolversion (unknown source)
At org. Apache. hadoop. IPC. rpc. getproxy (rpc. Java: 364)
At org. Apache. hadoop. HDFS. dfsclient. createrpcnamenode (dfsclient. Java: 106)
At org. Apache. hadoop. HDFS. dfsclient. <init> (dfsclient. Java: 208)
At org. Apache. hadoop. HDFS. dfsclient. <init> (dfsclient. Java: 175)
At org. Apache. hadoop. HDFS. distributedfilesystem. initialize (distributedfilesystem. Java: 89)
At org. Apache. hadoop. fs. filesystem. createfilesystem (filesystem. Java: 1310)
At org. Apache. hadoop. fs. filesystem. Access $100 (filesystem. Java: 65)
At org. Apache. hadoop. fs. filesystem $ cache. Get (filesystem. Java: 1328)
At org. Apache. hadoop. fs. filesystem. Get (filesystem. Java: 226)
At filesystemcat. Main (filesystemcat. Java: 20)
... 10 more
Caused by: java.net. connectexception: Connection refused
At sun. NiO. Ch. socketchannelimpl. checkconnect (native method)
At sun. NiO. Ch. socketchannelimpl. finishconnect (socketchannelimpl. Java: 567)
At org.apache.hadoop.net. socketiowithtimeout. Connect (socketiowithtimeout. Java: 206)
At org.apache.hadoop.net. netutils. Connect (netutils. Java: 406)
At org. Apache. hadoop. IPC. Client $ connection. setupconnection (client. Java: 414)
At org. Apache. hadoop. IPC. Client $ connection. setupiostreams (client. Java: 527)
At org. Apache. hadoop. IPC. Client $ connection. Access $1800 (client. Java: 187)
At org. Apache. hadoop. IPC. Client. getconnection (client. Java: 1164)
At org. Apache. hadoop. IPC. Client. Call (client. Java: 1010)
... 22 more

[Solution]

Add port 9000 to uri. Do not use 127.0.0.1 for localhost.

$ Bin/hadoop jar ~ /Desktop/filesystemcat. Jar HDFS: // localhost: 9000/user/Ubuntu/output/part-00000

[Reference]

Http://sileryang.wordpress.com/2011/05/24/%E6%8F%90%E4%BA%A4%E4%B8%80%E4%B8%AAhadoop%E4%BD%9C%E4%B8%9A%E6%97%B6%E8%BF%94%E5%9B%9Eipc-client-retrying-connect-to-server/