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
