hadoop java compatability

[Augustine Calvino]

I want to know what java versions are compatible with the latest hadoop.
The most that the documentation

says
is to check the wiki
,
which is obviously out of date since it only is listing java 6 and 7. That
wiki has a link to another wiki page
,
which is more helpful, as it actually lists the compatible versions of
java. However, it doesn't say which jdk's/jvm's are supported (Oracle vs
OpenJDK, vs AdoptOpenJDK, or hotspot vs open-j9). Also, that page says that
hadoop 3 is only compatible with java 8, but Cloudera's CDH 6, which uses

hadoop
3, apparently supports

 openjdk11.

We would really like to use java 11 with our new hadoop builds due to the
improved garbage collection, and would also prefer to use non-oracle jdk
builds, but the messaging about what is supported seems sparse and
sometimes contradictory.  Any clarification would be appreciated.

Thanks!

- Augustine

Re: hadoop java compatability

[Akira Ajisaka]

Hi Augustine,

Java 11 is not supported even in the latest version in Apache Hadoop.
I hope Apache Hadoop 3.3.0 will support Java 11 (only runtime support) but
3.3.0 is not released yet.
(Our company (Yahoo! JAPAN) builds trunk with OpenJDK 8 and run HDFS dev
cluster with OpenJDK 11 successfully.)

CDH 6 backports some patches from trunk and that's why it supports
openjdk11.

> Which jdks's/jvm's are supported
Now Apache Hadoop is using OpenJDK for build environment, and that's why
OpenJDK should be supported in the community.
https://github.com/apache/hadoop/blob/rel/release-3.2.1/dev-support/docker/Dockerfile#L92
Other jdk's/jvm's should work well, but I think they are not officially
supported.

I'll update the wiki to include that information.

Regards,
Akira


On Wed, Dec 4, 2019 at 3:36 AM Augustine Calvino 
wrote:

> I want to know what java versions are compatible with the latest hadoop.
> The most that the documentation
> 
>  says
> is to check the wiki
> ,
> which is obviously out of date since it only is listing java 6 and 7. That
> wiki has a link to another wiki page
> ,
> which is more helpful, as it actually lists the compatible versions of
> java. However, it doesn't say which jdk's/jvm's are supported (Oracle vs
> OpenJDK, vs AdoptOpenJDK, or hotspot vs open-j9). Also, that page says that
> hadoop 3 is only compatible with java 8, but Cloudera's CDH 6, which uses
> 
>  hadoop
> 3, apparently supports
> 
>  openjdk11.
>
> We would really like to use java 11 with our new hadoop builds due to the
> improved garbage collection, and would also prefer to use non-oracle jdk
> builds, but the messaging about what is supported seems sparse and
> sometimes contradictory.  Any clarification would be appreciated.
>
> Thanks!
>
> - Augustine
>