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From Tsuyoshi Ozawa <oz...@apache.org>
Subject Re: [DISCUSS] About the details of JDK-8 support
Date Tue, 06 Oct 2015 01:43:13 GMT
I forgot to mention - we also need to upgrade Google Guice to 0.4.0
for source-level JDK8 support in addition to asm and cglib.


> Some highlights:
> Java8 runtime compatibility for Guice core & all extensions.

Best regards,
- Tsuyoshi

On Tue, Oct 6, 2015 at 9:35 AM, Tsuyoshi Ozawa <ozawa@apache.org> 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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