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From Masatake Iwasaki <iwasak...@oss.nttdata.co.jp>
Subject Re: [DISCUSS] About the details of JDK-8 support
Date Wed, 07 Oct 2015 06:29:23 GMT
Thanks for clear summary, Tsuyoshi.

I read some related past discussions.

   https://wiki.apache.org/hadoop/MovingToJdk7and8
   http://search-hadoop.com/m/uOzYtGSiCs1acRnh
   http://search-hadoop.com/m/uOzYthdWJqpGdSZ1

Though there seems to be no consensus about when to drop java 7 support yet,
it would not be 2.8 for which the preparation is already started.
If the works for making source compatible with java 8 does not result in
dropping java 7 support, it would be nice and easy to backport to branch-2.


 > we need to upgrade grizzly to 2.2.16 to use
 > jersey-test-framework-grizzly2. I’d like to discuss which version we
 > will target this change. Can we do this in branch-2?

At lease, the newest grizzly, jersey and asm seems to support java 7 too
and HADOOP-11993 may work in branch-2.


Masatake Iwasaki


On 10/6/15 09:35, Tsuyoshi Ozawa wrote:
 > Hi commiters and users of Hadoop stack,
 >
 > I’ll share the current status of JDK-8 support here. We can take a
 > two-step approach to support JDK-8 - runtime-level support and
 > source-level support.
 >
 > About runtime-level support, I’ve tested Hadoop stack with JDK-8  e.g.
 > MapReduce, Spark, Tez, Flink on YARN and HDFS for a few months. As
 > long as I tested, it works well completely since JDK-8 doesn’t have
 > any incompatibility at binary level. We can say Hadoop has supported
 > JDK8 runtime already. Do you have any concern about this? I’ve not
 > tested with HBase yet. I need help of HBase community. I think only
 > problem about runtime is HADOOP-11364, default value of
 > colntainer-killer of YARN. After fixing the issue, we can declare the
 > support of JDK on Hadoop Wiki to make it clear for users.
 > https://wiki.apache.org/hadoop/HadoopJavaVersions
 >
 > About source-level, however, we have one big problem - upgrading
 > dependency of asm and cglib. We need to upgrade all libraries which
 > depends on asm to support new byte code introduced in JDK8[1]. The
 > dependencies which uses asm are jersey-server for compile and provide
 > scope, and cglib for test scope(I checked it with mvn dependency:tree
 > command). HADOOP-9613 is addressing the problem.
 >
 > One complex problem I’ve faced is Jersey depends on grizzly - to
 > upgrade jersey to 1.19, which supports JDK8,
 >  we need to upgrade grizzly to 2.2.16 to use
 > jersey-test-framework-grizzly2. I’d like to discuss which version we
 > will target this change. Can we do this in branch-2? Should we take
 > care of HADOOP-11656 and HADOOP-11993 at the same time? I’d also
 > confirm whether HADOOP-11993 means to remove Jersey, which depends on
 > asm, or not. I think we can collaborate with Yetus community here.
 >
 > Also, another simple problem is that source code cannot be compiled
 > because javadoc format or variable identifier are illegal(e.g.
 > HADOOP-12457, HADOOP-11875). I think this can be solved
 > straightforwardly.
 >
 > Please share any concern I’ve missed. The opinions of users are also 
welcome :-)
 > I'd like to go forward this step by step to make Hadoop user friendly.
 >
 > Thanks Steve, Sean, Allen, Robert, Brahma, Akira, Larry, Allen, Andrew
 > Purtell, Tsz-wo Sze, Sethen and other guys for having lots works about
 > JDK-8.
 >
 > Best regards,
 > - Tsuyoshi
 >
 > [1] http://product.hubspot.com/blog/upgrading-to-java-8-at-scale
 > [2] http://ispras.linuxbase.org/index.php/Java_API_Compliance_Checker


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