apache - Hadoop client not able to connect to server -


i set 2-node hadoop cluster, , running start-df.sh , start-yarn.sh works nicely (i.e. expected services running, no errors in logs).

however, when try run application, several tasks fail:

15/04/01 15:27:53 info mapreduce.job: task id : attempt_1427894767376_0001_m_000008_2, status : failed

i checked yarn , datanode logs, nothing reported there. in userlogs, syslogs files on slave node contain following error message:

2015-04-01 15:27:21,077 info [main] org.apache.hadoop.ipc.client: retrying connect server: slave.domain.be./127.0.1.1:53834. tried 9 time(s); retry policy retryuptomaximumcountwithfixedsleep(maxretries=10, sleeptime=1000 milliseconds) 2015-04-01 15:27:21,078 warn [main] org.apache.hadoop.mapred.yarnchild: exception running child : java.net.connectexception: call slave.domain.be./127.0.1.1 slave.domain.be.:53834 failed on connection exception: java.net.connectexception: connection refused; more details see: http://wiki.apache.org/hadoop/connectionrefused @ sun.reflect.nativeconstructoraccessorimpl.newinstance0(native method)

so problem slave cannot connect itself..

i checked whether there process running on slave node listening @ port 53834, there none. however, 'expected' ports being listened on (50020,50075,..). in configuration have used port 53834. it's different port on different runs.

any ideas on fixing issue?

your error might due loopback address in hosts file. go /etc/hosts file , comment line 127.0.1.1 in slave nodes , master node(if necessary). start hadoop processes.

edited:

  1. do in terminal edit hosts file without root permission: sudo bash

  2. enter current user password enter root login. can edit hosts file using: nano /etc/hosts


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