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https://issues.apache.org/jira/browse/HADOOP-12574?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15008067#comment-15008067
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Allen Wittenauer commented on HADOOP-12574:
-------------------------------------------
This is already fixed in trunk as part of HADOOP-9902. In addition to the
problems noted above, there are also the re-eval HADOOP_OPTS problem which
ultimately makes this impossible to fix in branch-2 without breaking
compatibility.
> Multiple Xmx Parameters to Java Process
> ---------------------------------------
>
> Key: HADOOP-12574
> URL: https://issues.apache.org/jira/browse/HADOOP-12574
> Project: Hadoop Common
> Issue Type: Bug
> Affects Versions: 2.7.1
> Reporter: Jonathan Ellithorpe
>
> When launching hadoop, the setting of environment variable HADOOP_HEAPMAX
> results in multiple Xmx parameters being passed to the java application
> launcher. This is because a default Xmx setting included in the
> HADOOP_CLIENT_OPTS in etc/hadoop/hadoop-env.sh, line 61:
> # The following applies to multiple commands (fs, dfs, fsck, distcp etc)
> export HADOOP_CLIENT_OPTS="-Xmx512m $HADOOP_CLIENT_OPTS"
> is merged into the variable HADOOP_OPTS in bin/hadoop, line 160:
> # Always respect HADOOP_OPTS and HADOOP_CLIENT_OPTS
> HADOOP_OPTS="$HADOOP_OPTS $HADOOP_CLIENT_OPTS"
> Orthogonally, the HADOOP_HEAPMAX environment variable triggers the setting of
> JAVA_HEAP_MAX in hadoop-config.sh, line 192:
> # check envvars which might override default args
> if [ "$HADOOP_HEAPSIZE" != "" ]; then
> #echo "run with heapsize $HADOOP_HEAPSIZE"
> JAVA_HEAP_MAX="-Xmx""$HADOOP_HEAPSIZE""m"
> #echo $JAVA_HEAP_MAX
> fi
> Which is ultimately passed to the java application launcher in bin/hadoop,
> line 166:
> exec "$JAVA" $JAVA_HEAP_MAX $HADOOP_OPTS $CLASS "$@"
> The result: two Xmx settings passed to the Java application launcher. Which
> one is respected depends on the JVM, but for HotSpot the rightmost setting is
> respected, and so the HADOOP_HEAPMAX environment variable has no effect and
> the default setting in HADOOP_CLIENT_OPTS wins.
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