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From Scott Carey <sc...@richrelevance.com>
Subject Re: Java Versions and Hadoop
Date Mon, 10 Oct 2011 04:22:16 GMT


On 10/8/11 11:19 AM, "Ted Dunning" <tdunning@maprtech.com> wrote:

>I hate to sound like the folks who only recently stopped using 1.4, but I
>am
>afraid that Todd is right on here.
>
>The folks who are desperate for new features are being siphoned off by
>Scala
>and Clojure which is leaving a core of recalcitrant termagants like me.  I
>think that it is going to take something as major as the EOL of Java 6 to
>get big projects to allow code that requires Java 7.


That was not the original user's question.  The question was not "When
will Hadoop REQUIRE Java 7" but "When will Hadoop SUPPORT using a Java 7
JRE".


The JVM in Java 7 is near identical to Java 6.  Sun/Oracle started
updating the JVM for JRE 6 to lag slightly (6-12 weeks) behind the (then
in development) Java 7 about 3 years ago.  After the next Java 6 update,
they will essentially be identical other than a handful of default
parameters and the presence of the invokevirtual JVM infrastructure.
The JDK has changed in many ways however -- there may be more risk there
over the next year than differences in the JVM.

Next, now that Hadoop is using Maven, it would be trivial to create a new
(optional) module that required Java 7 and provided useful things, like an
implementation of the new Java 7 File System API for HDFS.  Hadoop would
not require a Java 7 JRE, but a user that was using a Java 7 JRE would
have some extra API's available.

Java 8 will be a bigger beast that will likely result in more demands for
Hadoop to adopt somewhat rapidly.
Project Lambda will result in many requests for API enhancements around
Map/Reduce.
Project Jigsaw may finally rescue Hadoop from itself and allow proper
isolation of user code from framework code.


>
>On Sat, Oct 8, 2011 at 2:00 AM, Todd Lipcon <todd@cloudera.com> wrote:
>
>> I think requiring Java 7 is years off... I think most people have
>> doubts as to Java 7's stability until it's been adopted by a majority
>> of applications, and the new features aren't compelling enough to jump
>> ship, IMO.
>>
>> -Todd
>>
>> On Fri, Oct 7, 2011 at 3:33 PM,  <Milind.Bhandarkar@emc.com> wrote:
>> > Hi Folks,
>> >
>> > While I have seen the wiki on which java versions to use currently to
>>run
>> > Hadoop, I have not seen any discussion about the roadmap of java
>>version
>> > compatibility with future hadoop versions.
>> >
>> > Recently, Oracle retired the "Operating System Distributor License for
>> > Java" (DLJ) [http://robilad.livejournal.com/90792.html,
>> > http://jdk-distros.java.net/] and Linux vendors have started making
>> > OpenJDK (6/7) as the default java version bundled with their OSs
>> > [http://www.java7developer.com/blog/?p=361]. Also, all future Java SE
>> > updates will be delivered through OpenJDK updates project.
>> >
>> > I see that OpenJDK6 (6b20pre) cannot be used to compile hadoop trunk.
>>Has
>> > anyone tried OpenJDK7 ?
>> >
>> > Additionally, I have a few small projects in mind which can really
>>make
>> > use of the new (esp I/O) features of Java 7.
>> >
>> > What, if any, timeline do hadoop developers have in mind to make Java
>>7
>> as
>> > required (and tested with OpenJDK 7) ?
>> >
>> > Thanks,
>> >
>> > - milind
>> >
>> > ---
>> > Milind Bhandarkar
>> > Greenplum Labs, EMC
>> > (Disclaimer: Opinions expressed in this email are those of the author,
>> and
>> > do not necessarily represent the views of any organization, past or
>> > present, the author might be affiliated with.)
>> >
>> >
>>
>>
>>
>> --
>> Todd Lipcon
>> Software Engineer, Cloudera
>>


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