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https://issues.apache.org/jira/browse/HADOOP-9870?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13739896#comment-13739896
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Allen Wittenauer commented on HADOOP-9870:
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Is there something inherently wrong with letting the JVM make the decision?
Are we worried about a JVM that doesn't follow the same set of rules? (which,
at this point, is a de facto API)
> Mixed configurations for JVM -Xmx in hadoop command
> ---------------------------------------------------
>
> Key: HADOOP-9870
> URL: https://issues.apache.org/jira/browse/HADOOP-9870
> Project: Hadoop Common
> Issue Type: Bug
> Reporter: Wei Yan
>
> When we use hadoop command to launch a class, there are two places setting
> the -Xmx configuration.
> *1*. The first place is located in file
> {{hadoop-common-project/hadoop-common/src/main/bin/hadoop}}.
> {code}
> exec "$JAVA" $JAVA_HEAP_MAX $HADOOP_OPTS $CLASS "$@"
> {code}
> Here $JAVA_HEAP_MAX is configured in hadoop-config.sh
> ({{hadoop-common-project/hadoop-common/src/main/bin/hadoop-config.sh}}). The
> default value is "-Xmx1000m".
> *2*. The second place is set with $HADOOP_OPTS in file
> {{hadoop-common-project/hadoop-common/src/main/bin/hadoop}}.
> {code}
> HADOOP_OPTS="$HADOOP_OPTS $HADOOP_CLIENT_OPTS"
> {code}
> Here $HADOOP_CLIENT_OPTS is set in hadoop-env.sh
> ({{hadoop-common-project/hadoop-common/src/main/conf/hadoop-env.sh}})
> {code}
> export HADOOP_CLIENT_OPTS="-Xmx512m $HADOOP_CLIENT_OPTS"
> {code}
> Currently the final default java command looks like:
> {code}java -Xmx1000m .... -Xmx512m CLASS_NAME ARGUMENTS"{code}
> And if users also specify the -Xmx in the $HADOOP_CLIENT_OPTS, there will be
> three -Xmx configurations.
> The hadoop setup tutorial only discusses hadoop-env.sh, and it looks that
> users should not make any change in hadoop-config.sh.
> We should let hadoop smart to choose the right one before launching the java
> command, instead of leaving for jvm to make the decision.
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