I am using a HDP 2.4.2 cluster, since yesterday few of my datanodes heap size has been up continuously even when there are no jobs running. I have seen this article:
but not sure where exactly to make these changes??
do i go to hadoop-env template on ambari and change the HADOOP_DATANODE_OPTS=...
And once i do it, do i need to restart the HDFS service??
@apappu is correct. These JVM options should be added to HADOOP_DATANODE_OPTS in the hadoop-env template.
After making the changes you should restart all the DataNodes (there is no need to restart the NameNodes). I recommend restarting DataNodes two at a time.