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8021 failed on connection exception: java.net.ConnectException: Connection refused         at org.apache.hadoop.ipc.Client.wrapException(Client.java:1095)

Question asked by chwaqas on May 15, 2012
Latest reply on May 15, 2012 by nabeel
Hi I am trying to configure Hadoop 1.0. in pseudodistributed mode by following this blog.

http://hadoop-tutorial.blogspot.de/2010/11/running-hadoop-in-pseudo-distributed.html?showComment=1337083501000#c615470573579885293.

But when I run the pi example given in the hadoop distribution, I get the error mentioned in title. Can someone please help me and guide me how can I fix this problem. Also its a request that please suggest solution as well if possible along with pinpinting the problem. Here is complete error message.

 

    Number of Maps  = 10
    Samples per Map = 100
    Wrote input for Map #0
    Wrote input for Map #1
    Wrote input for Map #2
    Wrote input for Map #3
    Wrote input for Map #4
    Wrote input for Map #5
    Wrote input for Map #6
    Wrote input for Map #7
    Wrote input for Map #8
    Wrote input for Map #9
    Starting Job
    12/05/16 13:11:56 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 0 time(s).
    12/05/16 13:11:57 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 1 time(s).
    12/05/16 13:11:58 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 2 time(s).
    12/05/16 13:11:59 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 3 time(s).
    12/05/16 13:12:00 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 4 time(s).
    12/05/16 13:12:01 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 5 time(s).
    12/05/16 13:12:02 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 6 time(s).
    12/05/16 13:12:03 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 7 time(s).
    12/05/16 13:12:04 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 8 time(s).
    12/05/16 13:12:05 INFO ipc.Client: Retrying connect to server: localhost/127.0.0.1:8021. Already tried 9 time(s).
    java.net.ConnectException: Call to localhost/127.0.0.1:8021 failed on connection exception: java.net.ConnectException: Connection refused
            at org.apache.hadoop.ipc.Client.wrapException(Client.java:1095)
            at org.apache.hadoop.ipc.Client.call(Client.java:1071)
            at org.apache.hadoop.ipc.RPC$Invoker.invoke(RPC.java:225)
            at org.apache.hadoop.mapred.$Proxy2.getProtocolVersion(Unknown Source)
            at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:396)
            at org.apache.hadoop.ipc.RPC.getProxy(RPC.java:379)
            at org.apache.hadoop.mapred.JobClient.createRPCProxy(JobClient.java:480)
            at org.apache.hadoop.mapred.JobClient.init(JobClient.java:474)
            at org.apache.hadoop.mapred.JobClient.<init>(JobClient.java:457)
            at org.apache.hadoop.mapred.JobClient.runJob(JobClient.java:1260)
            at org.apache.hadoop.examples.PiEstimator.estimate(PiEstimator.java:297)
            at org.apache.hadoop.examples.PiEstimator.run(PiEstimator.java:342)
            at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:65)
            at org.apache.hadoop.examples.PiEstimator.main(PiEstimator.java:351)
            at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
            at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
            at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
            at java.lang.reflect.Method.invoke(Method.java:601)
            at org.apache.hadoop.util.ProgramDriver$ProgramDescription.invoke(ProgramDriver.java:68)
            at org.apache.hadoop.util.ProgramDriver.driver(ProgramDriver.java:139)
            at org.apache.hadoop.examples.ExampleDriver.main(ExampleDriver.java:64)
            at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
            at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
            at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
            at java.lang.reflect.Method.invoke(Method.java:601)
            at org.apache.hadoop.util.RunJar.main(RunJar.java:156)
    Caused by: java.net.ConnectException: Connection refused
            at sun.nio.ch.SocketChannelImpl.checkConnect(Native Method)
            at sun.nio.ch.SocketChannelImpl.finishConnect(SocketChannelImpl.java:701)
            at org.apache.hadoop.net.SocketIOWithTimeout.connect(SocketIOWithTimeout.java:206)
            at org.apache.hadoop.net.NetUtils.connect(NetUtils.java:656)
            at org.apache.hadoop.ipc.Client$Connection.setupConnection(Client.java:434)
            at org.apache.hadoop.ipc.Client$Connection.setupIOstreams(Client.java:560)
            at org.apache.hadoop.ipc.Client$Connection.access$2000(Client.java:184)
            at org.apache.hadoop.ipc.Client.getConnection(Client.java:1202)
            at org.apache.hadoop.ipc.Client.call(Client.java:1046)
            ... 24 more

Here is the output when i run jps

    8322 Jps
    7611 SecondaryNameNode
    7474 DataNode
    7341 NameNode

Outcomes