Yarn

Yet Another Resource Negotiator.

Problem#1: while tying to check log from application hisory ui > mapper/reducer log, got error

Aggregation is not enabled. Try the nodemanager at.

Sol: adding property "yarn.log-aggregation-enable"="true" to yarn-site.xml in all nodes helped.

Problem#2: Error "org.apache.hadoop.hbase.exceptions.OutOfOrderScannerNextException ... was there rpc timeout" for large row read.

Sol: check hbase mapreduce

Problem#3: Container got killed with non-zero exit code.

Sol: No errors were found, finally re-installing yarn service helped.

Problem#4: Error while submitting application to yarn. "Exception in thread "main" java.lang.UnsupportedClassVersionError: SOME_PACKAGE/SOME_CLASS : Unsupported major.minor version 51.0 ."

Sol: Installed jdk 1.7.0_71, and updated JAVA_HOME in bashrc/bash.bashrc to use same. earlier JAVA_HOME was pointing to default which was pointing to jdk1.6.. Later restarted yarn.