[HADOOP-10245] Hadoop command line always appends "-Xmx" option twice

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 2.2.0
• Component/s: bin, scripts
• Assignee: shanyu zhao
• Reporter: shanyu zhao
• Created: 20/Jan/14 23:30
• Updated: 08/Feb/15 17:42
• Resolved: 08/Feb/15 17:42

Description

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:
export HADOOP_CLIENT_OPTS="-Xmx512m $HADOOP_CLIENT_OPTS"

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.

Issue Links

• is duplicated by: HADOOP-9902 Shell script rewrite