shanyu zhao created HADOOP-10245:
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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:
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.
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