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https://issues.apache.org/jira/browse/HADOOP-10245?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13877905#comment-13877905
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shanyu zhao commented on HADOOP-10245:
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[~ywskycn] Thank you for your comment! If we remove -Xmx512m from
HADOOP_CLIENT_OPTS in hadoop_env.cmd, there will be one and only one -Xmx,
which is the $JAVA_HEAP_MAX in bin/hadoop.
HADOOP-9870 may have solved the problem for you, but I think the fix in
HADOOP-9870 might be too complicated and hard to maintain. For example, what
about user use "-Xmx" in HADOOP_OPTS instead of HADOOP_CLIENT_OPTS? I think we
should avoid using HADOOP_CLIENT_OPTS or HADOOP_OPTS to specify memory, because
the fact that we've defined HADOOP_HEAPSIZE but not using it for memory
specification is confusing. If you want to change heap size, just change
HADOOP_HEAPSIZE, I think this is simple and clear. Thoughts?
> 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
> Attachments: HADOOP-10245.patch
>
>
> 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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