Changing the Logging Configuration

For DAGAppMasters and ContainerWorkers of MR3, Hive-MR3 uses a logging configuration file (`mr3-container-log4j.properties`) included in the Hive-MR3 distribution by default: ```properties mr3.root.logger=INFO, console, file log4j.rootLogger=${mr3.root.logger} log4j.appender.console=org.apache.log4j.ConsoleAppender log4j.appender.console.layout=org.apache.log4j.PatternLayout log4j.appender.console.layout.ConversionPattern=%d [%t] %-5p %c %x - %m%n log4j.appender.console.Threshold=ERROR log4j.appender.file=org.apache.log4j.RollingFileAppender log4j.appender.file.MaxFileSize=100MB log4j.appender.file.MaxBackupIndex=100 log4j.appender.file.layout=org.apache.log4j.PatternLayout log4j.appender.file.layout.ConversionPattern=%d [%t] %-5p %c %x - %m%n log4j.appender.file.File=${yarn.app.container.log.dir}/run.log log4j.appender.file.Append=false log4j.appender.file.Threshold=ALL ``` The user can change the logging level by resetting the environment variable `LOG_LEVEL` in `env.sh`: ```sh LOG_LEVEL=INFO ``` The user can also use a different logging configuration file by updating command-line options for DAGAppMaster and ContainerWorkers specified in `hive-site.xml`: ```xml mr3.am.launch.cmd-opts ${am.honestopts} ${am.jfropts1} ${am.jfropts2} ${am.jfropts3} ${am.jfropts4} ${am.jfropts5} ${am.jfropts6} ${am.yourkitopts} -server -Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN -XX:+PrintGCDetails -verbose:gc -XX:+PrintGCTimeStamps -XX:+UseNUMA -XX:+UseG1GC -XX:+ResizeTLAB mr3.container.launch.cmd-opts ${container.honestopts} ${container.jfropts1} ${container.jfropts2} ${container.jfropts3} ${container.jfropts4} ${container.jfropts5} ${container.jfropts6} ${container.yourkitopts} -server -Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN -XX:+PrintGCDetails -verbose:gc -XX:+PrintGCTimeStamps -XX:NewRatio=8 -XX:+UseNUMA -XX:+UseG1GC -XX:+ResizeTLAB ``` `mr3.am.launch.cmd-opts` specifies commad-line options for DAGAppMasters and `mr3.container.launch.cmd-opts` specifies command-line options for ContainerWorkers. Thus the user can append a new command-line option `-Dlog4j.configuration=`. The user should make sure that that the new logging configuration file is found in the classpath.