Java in a docker container

[Volker Simonis]

On Wed, Dec 14, 2016 at 11:36 PM, kant kodali <kanth909 at gmail.com> wrote:
> Hi Brian,
>
> If you think it is insufficiency of Docker then perhaps one may want to
> look at how things are done in other Languages such as Go and so on? I just
> don't why Java is targeted all the time when I hear from people saying "No
> one puts Java in a container". My mind immediately thinks is it only Java
> or any VM based language.

I think part of the problem is that Java is one of the most
sophisticated VMs (and unfortunately this sometimes translates into
most most heavy-weight VMs :( It has two JIT compilers, several quite
complex GC implementations which are by far better than the ones from
other VM based languanges and a huge class library. This all adds up
to a relatively big footprint and relatively slow startup.

For example Java was newer designed for executing something like
shell-scripts and the built-in ergonomics aren't designed to optimize
the VM for such scenarios. They are better suited for web servers or
heavy-weight applications like IDEs and they mostly assume they can
grab most of the resources of the machine they are running on.

I think these are the reasons why other scripting or VM-based
languages run better "by default" in container enviroments - they
simple need fewer resources by default. But I think Java can be tuned
in the same way - we just have to do it :)

Regards,
Volker

>
> thanks,
> kant
>
>
> On Wed, Dec 14, 2016 at 8:48 AM, Brian Burkhalter <
> brian.burkhalter at oracle.com> wrote:
>
>> There are also container-related issues in Java NIO [1]. I spent a
>> not-insignificant amount of time on this a few months ago but a solution
>> was elusive and we let it drop for JDK 9. I am not convinced that the
>> fundamental problem is not due to an insufficiency of Docker itself. There
>> are several issues linked from [1] among which the Docker-specific one is
>> [2].
>>
>> Regards,
>>
>> Brian
>>
>> [1] http://mail.openjdk.java.net/pipermail/nio-dev/2016-
>> October/003915.html
>> [2] https://bugs.openjdk.java.net/browse/JDK-8165852
>>
>> On Dec 13, 2016, at 12:14 AM, Volker Simonis <volker.simonis at gmail.com>
>> wrote:
>>
>> > […] and there's another Enhancement request open for this topic:
>> >
>> > 8146115: physical memory does not see Docker resource limits
>> > https://bugs.openjdk.java.net/browse/JDK-8146115
>> >
>> > Please feel free to contribute any insights from your side to this
>> discussions.
>>
>>