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HDFS >> mail # dev >> Re: Moving to JDK7, JDK8 and new major releases


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Re: Moving to JDK7, JDK8 and new major releases
On Jun 24, 2014, at 4:22 PM, Andrew Wang <[EMAIL PROTECTED]> wrote:

I think there is a some confusion/misunderstanding here.

With hadoop-2 the user is completely in control of his own classpath (we had a similar, but limited capability in hadoop-1 w/ https://issues.apache.org/jira/browse/MAPREDUCE-1938).

Furthermore, it's probably not well known that in hadoop-2 the user application (MR or otherwise) can also pick the JDK version by using JAVA_HOME env for the container. So, in effect, MR applications can continue to use java6 while YARN is running java7 - this hasn't been tested extensively though. This capability did not exist in hadoop-1. We've also made some progress with https://issues.apache.org/jira/browse/MAPREDUCE-1700 to defuse user jar-deps from MR system jars. https://issues.apache.org/jira/browse/MAPREDUCE-4421 also helps by ensuring MR applications can pick exact version of MR jars they were compiled against; and not rely on cluster installs.

Hope that helps somewhat.

thanks,
Arun
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