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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "HadoopJavaVersions" by SteveLoughran
Date Fri, 09 Apr 2010 09:01:10 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "HadoopJavaVersions" page has been changed by SteveLoughran.
The comment on this change is: New page on Java versions.
http://wiki.apache.org/hadoop/HadoopJavaVersions

--------------------------------------------------

New page:
= Hadoop Java Versions =

Hadoop requires Java 1.6+. It is built and tested on Sun Java, which is the only "supported"
JVM.

If you have a problem with Hadoop, and you are running anything other than the official Sun
JDK, you are likely to be asked to try and run Hadoop on the Sun JDK/JVM, to see if the problem
goes away. That said, patches that help Hadoop run on other JVMs ''which do not effect the
stability or performance of Hadoop on the Sun JVM'' are encouraged. 

== Sun JDK ==

Problems were reported with Java 1.6u18; consensus was: avoid. As Java 1.6u19 includes a lot
of security fixes, as well as the 1.6u18 changes, this raises some concerns. If you are running
Hadoop on 1.6u15, you must examine the security problems patched in the later version(s),
and consider whether they are needed.


== OpenJDK ==

Hadoop does build and run on OpenJDK. 

OpenJDK is handy to have on a development system as it has more source for you to step into
when debugging something. OpenJDK and Sun JDK mainly differ in (native?) rendering/AWT/Swing
code, which is not relevant for any MapReduce Jobs that aren't creating images as part of
their work.

== Oracle JRockit ==

Hadoop has been used on JRockit, though maybe not at "production" scale. 

 1. [[http://forums.oracle.com/forums/thread.jspa?messageID=3474253|Problems spawning jobs]]
 1. [[https://issues.apache.org/jira/browse/MAPREDUCE-593|One of the tests doesn't like JRockit]]
 1. [[https://issues.apache.org/jira/browse/HADOOP-3654|Log4J configuration issues]]

== IBM JDK ==

We have no data on this, contributions welcome!

== Apache Harmony ==

We have not yet got Hadoop to [[https://issues.apache.org/jira/browse/HADOOP-3262|compile
under Harmony]], though we look forward to having a complete Apache Java/Hadoop runtime.

== A request for help from JVM/JDK developers ==

We would strongly encourage anyone who produces a JVM/JDK to test compiling and running Hadoop
with it. It makes for a fantastic performance and stress test. As Hadoop is becoming a key
back-end datacenter application, good Hadoop support matters.

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