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https://issues.apache.org/jira/browse/HADOOP-9424?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15414532#comment-15414532
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Sangjin Lee commented on HADOOP-9424:
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Coming over from HADOOP-13410, I would rather take the opposite approach.
What's included in HADOOP_CLASSPATH should be considered more like "user
classes". I would rather put the content of HADOOP_CLASSPATH in the user
classloader that loads the jar and remove it from the CLASSPATH. That way, the
jar in the argument and the content of the HADOOP_CLASSPATH would be visible to
each other. Note that the isolated classloading (HADOOP_CLIENT_CLASSLOADER)
already takes that approach.
> The "hadoop jar" invocation should include the passed jar on the classpath as
> a whole
> -------------------------------------------------------------------------------------
>
> Key: HADOOP-9424
> URL: https://issues.apache.org/jira/browse/HADOOP-9424
> Project: Hadoop Common
> Issue Type: Bug
> Components: util
> Affects Versions: 2.0.3-alpha
> Reporter: Harsh J
> Assignee: Harsh J
> Priority: Minor
> Labels: BB2015-05-TBR
> Attachments: HADOOP-9424.patch
>
>
> When you have a case such as this:
> {{X.jar -> Classes = Main, Foo}}
> {{Y.jar -> Classes = Bar}}
> With implementation details such as:
> * Main references Bar and invokes a public, static method on it.
> * Bar does a class lookup to find Foo (Class.forName("Foo")).
> Then when you do a {{HADOOP_CLASSPATH=Y.jar hadoop jar X.jar Main}}, the
> Bar's method fails with a ClassNotFound exception cause of the way RunJar
> runs.
> RunJar extracts the passed jar and includes its contents on the ClassLoader
> of its current thread but the {{Class.forName(…)}} call from another class
> does not check that class loader and hence cannot find the class as its not
> on any classpath it is aware of.
> The script of "hadoop jar" should ideally include the passed jar argument to
> the CLASSPATH before RunJar is invoked, for this above case to pass.
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