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https://issues.apache.org/jira/browse/HADOOP-9450?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13621553#comment-13621553
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Chris Nauroth commented on HADOOP-9450:
---------------------------------------
Hi, Mitch. HADOOP_USER_CLASSPATH_FIRST has been working fine for me. What
version of the code are you running? I checked the trunk and branch-1 versions
of this code, and both seem to be correct. There are 3 snippets that are
relevant. First, CLASSPATH is initialized to HADOOP_CONF_DIR:
{code}
# CLASSPATH initially contains $HADOOP_CONF_DIR
CLASSPATH="${HADOOP_CONF_DIR}"
{code}
Second, there is a check if HADOOP_USER_CLASSPATH_FIRST and HADOOP_CLASSPATH
are defined. If defined, then the next thing becomes HADOOP_CLASSPATH. Note
that HADOOP_CONF_DIR would still be first, but this should be fine, because
jars/classes don't really go in the conf dir.
{code}
if [ "$HADOOP_USER_CLASSPATH_FIRST" != "" ] && [ "$HADOOP_CLASSPATH" != "" ] ;
then
CLASSPATH=${CLASSPATH}:${HADOOP_CLASSPATH}
fi
{code}
After this, there is logic for adding the various Hadoop classpath entries from
the build. Finally, there is a second check of HADOOP_USER_CLASSPATH_FIRST and
HADOOP_CLASSPATH:
{code}
# add user-specified CLASSPATH last
if [ "$HADOOP_USER_CLASSPATH_FIRST" = "" ] && [ "$HADOOP_CLASSPATH" != "" ];
then
CLASSPATH=${CLASSPATH}:${HADOOP_CLASSPATH}
fi
{code}
This is the opposite of the first check: if HADOOP_USER_CLASSPATH_FIRST and
HADOOP_CLASSPATH are undefined, then now we need to add them as the last
entries.
I think this all works correctly, but were you looking at a different version
of the code?
> HADOOP_USER_CLASSPATH_FIRST is not honored; CLASSPATH is PREpended instead of
> APpended
> --------------------------------------------------------------------------------------
>
> Key: HADOOP-9450
> URL: https://issues.apache.org/jira/browse/HADOOP-9450
> Project: Hadoop Common
> Issue Type: Bug
> Reporter: Mitch Wyle
>
> On line 133 of the hadoop shell wrapper, CLASSPATH is set as:
> CLASSPATH=${CLASSPATH}:${HADOOP_CLASSPATH}
> Notice that the built-up CLASSPATH, along with all the libs and unwanted JARS
> are pre-pended BEFORE the user's HADOOP_CLASSPATH. Therefore there is no way
> to put your own JARs in front of those that the hadoop wrapper script sets.
> We propose a patch that reverses this order. Failing that, we would like to
> add a command line option to override this behavior and enable a user's JARs
> to be found before the wrong ones in the Hadoop library paths.
> We always welcome your opinions.
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