Analyzing transitions through logs
Both YARN services, ResourceManager and NodeManager generate logs and store them in a .log file locally inside the folder specified using the HADOOP_LOGS_DIR variable. By default, the logs are stored in HADOOP_PREFIX/logs. All the state transitions in YARN are recorded in the log files. In this section, we'll cover few state transitions and the logs generated during those transitions.
Note
Setting the log level: Hadoop-YARN uses Apache Log4j library and it uses a log4j.properties file located in the configuration folder of the Hadoop-YARN bundle at HADOOP_PREFIX/etc/hadoop.
The Log4j library supports six log levels – TRACE, DEBUG, INFO, WARN, ERROR, and FATAL. A cluster administrator sets the log level for Hadoop-YARN ...
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