Environment variables for sizing NameNode heap memory

You can configure the values of HADOOP_HEAPSIZE and HADOOP_NAMENODE_OPTS to size the NameNode heap memory.

HADOOP_HEAPSIZE sets the JVM heap size for all Hadoop project servers such as HDFS, YARN, and MapReduce. HADOOP_HEAPSIZE is an integer passed to the JVM as the maximum memory (Xmx) argument. For example:
HADOOP_NAMENODE_OPTS is specific to the NameNode and sets all JVM flags, which must be specified. HADOOP_NAMENODE_OPTS overrides the HADOOP_HEAPSIZE Xmx value for the NameNode. For example:
HADOOP_NAMENODE_OPTS=-Xms1024m -Xmx1024m -XX:+UseParNewGC -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=70 -XX:+CMSParallelRemarkEnabled -XX:+PrintTenuringDistribution -XX:OnOutOfMemoryError={{AGENT_COMMON_DIR}}/killparent.sh

Both HADOOP_NAMENODE_OPTS and HADOOP_HEAPSIZE are stored in /etc/hadoop/conf/hadoop-env.sh.