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From "shanyu zhao (JIRA)" <j...@apache.org>
Subject [jira] [Created] (HADOOP-10245) Hadoop command line always appends "-Xmx" option twice
Date Mon, 20 Jan 2014 23:30:26 GMT
shanyu zhao created HADOOP-10245:

             Summary: Hadoop command line always appends "-Xmx" option twice
                 Key: HADOOP-10245
                 URL: https://issues.apache.org/jira/browse/HADOOP-10245
             Project: Hadoop Common
          Issue Type: Bug
          Components: bin
    Affects Versions: 2.2.0
            Reporter: shanyu zhao
            Assignee: shanyu zhao

The Hadoop command line scripts (hadoop.sh or hadoop.cmd) will call java with "-Xmx" options
twice. The impact is that any user defined HADOOP_HEAP_SIZE env variable will take no effect
because it is overwritten by the second "-Xmx" option.

For example, here is the java cmd generated for command "hadoop fs -ls /", Notice that there
are two "-Xmx" options: "-Xmx1000m" and "-Xmx512m" in the command line:

java -Xmx1000m  -Dhadoop.log.dir=C:\tmp\logs -Dhadoop.log.file=hadoop.log -Dhadoop.root.logger=INFO,c
onsole,DRFA -Xmx512m  -Dhadoop.security.logger=INFO,RFAS -classpath XXX org.apache.hadoop.fs.FsShell
-ls /

Here is the root cause:
The call flow is: hadoop.sh calls hadoop_config.sh, which in turn calls hadoop-env.sh. 
In hadoop.sh, the command line is generated by the following pseudo code:
java $JAVA_HEAP_MAX $HADOOP_CLIENT_OPTS -classpath ...

In hadoop-config.sh, $JAVA_HEAP_MAX is initialized as "-Xmx1000m" if user didn't set $HADOOP_HEAP_SIZE
env variable.

In hadoop-env.sh, $HADOOP_CLIENT_OPTS is set as this:

To fix this problem, we should remove the "-Xmx512m" from HADOOP_CLIENT_OPTS. If we really
want to change the memory settings we need to use $HADOOP_HEAP_SIZE env variable.

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