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From "Mark Tse (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HDFS-7255) Customize Java Heap min/max settings for individual processes
Date Thu, 16 Oct 2014 18:23:33 GMT
Mark Tse created HDFS-7255:

             Summary: Customize Java Heap min/max settings for individual processes
                 Key: HDFS-7255
                 URL: https://issues.apache.org/jira/browse/HDFS-7255
             Project: Hadoop HDFS
          Issue Type: Improvement
          Components: datanode, journal-node, namenode
    Affects Versions: 2.5.1, 2.4.1
            Reporter: Mark Tse

The NameNode and JournalNode (and ZKFC) can all run on the same machine. However, they get
their heap settings from HADOOP_HEAPSIZE/JAVA_HEAP_MAX. There are scenarios where the NameNode
process should have different Java memory requirements than the JournalNode and ZKFC (e.g.
if the machine has 10 GB of RAM, and I want the NameNode process to have 8 GB max). 

HADOOP_(.*)_OPTS variables exist for these processes and can be used to add the Xms and Xmx
tags, but because of how the default for JAVA_HEAP_MAX is set, it will always add '-Xmx1000m'
to the final call to start up the NameNode/JournalNode/ZKFC process, resulting in two different
Java heap settings (e.g. -Xmx1000m and -Xmx8g is used when starting the NameNode).

Note: HADOOP_HEAPSIZE is deprecated according to [HADOOP-10950]

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