GSoC 2015: I want to volunteer. need organization

Mario Torre neugens.limasoftware at
Wed Feb 18 08:03:02 UTC 2015

Hi Christopher,

I don't think I will have the time to run a whole organisation this
year, so I didn't apply this time.

Beside that, there are some interesting issues to have OpenJDK as
Mentoring Organisation, reason why I've been applying as IcedTea in
the previous years.

If you feel you would like to help and decide to organise it, I'll be
happy to assist you in the process, of course, so you could try to
propose IcedTea as a Mentoring Organisation and be the Administrative
contact (pending Google Approval).


2015-02-18 3:13 GMT+01:00 Christopher Friedt <chrisfriedt at>:
> Hi again Mario & (finally!) Martijn as well as the rest of the
> openjdk-adoption list,
> There are only 3 days left until the application deadline to be a
> mentoring organization for GSoC 2015 [1].
> I am entirely prepared to mentor a student in the process of creating
> and submitting a patchset to OpenJDK based on my FOSDEM presentation
> [2]. However, I must somehow be affiliated with a mentoring
> organization to do so. Technically, I could apply on behalf of my
> company, MMB Networks, but we aren't really an open-source company, I
> just tend to participate in a number of open-source projects (with
> approval and no conflict-of-interest, of course)
> Proposed Topic: VMFlexArray PatchSet for OpenJDK
> Although drawing to the Linux FrameBuffer was the primary focus of my
> FOSDEM talk, an incidental aspect of my JamVM / Classpath patchset,
> but practically the most important part is what I have called
> "VMFlexArrays".
> A blog post[3] from today describes why VMFlexArrays are so critical
> in a "mathematically complete" sense of correct functionality of the
> java.nio API. Consider (or even run) the following code snippet.
> $ cat
> import java.nio.*;
> import java.util.*;
> public class BufferFu {
>   public static void main( String[] arg ) {
>     byte[] ba = new byte[] { (byte) 0xaa, (byte) 0xbb, (byte) 0xcc,
> (byte) 0xdd };
>     ByteBuffer bb = ByteBuffer.wrap( ba );
>     IntBuffer ib = bb.asIntBuffer();
>     int[] ia = ib.array();
>     System.out.println( "ba: " + Arrays.asList( ba ) + ", ia: " +
> Arrays.asList( ia ));
>   }
> }
> $ java BufferFu
> Exception in thread "main" java.lang.UnsupportedOperationException
> at java.nio.IntBuffer.array(
> at BufferFu.main(
> Why can't we represent the same physical / virtual memory with two
> different array views when the backing storage is present and the
> technology is available?
> The patchset does not break or change the Java API, and in fact makes
> the Java API work _better_!
> VMFlexArrays also allow us to represent off-heap memory regions in
> perfectly type-safe, managed java array objects. Such off-heap regions
> include, but are not limited to
> * arrays allocated by native libraries using malloc(3)
> * special files like /dev/video0 mapped using mmap(2)
> * process-specific heaps mapped using mmap(2)
> The goal of the GSoC project is challenging, demanding, but would
> greatly benefit the community at large.
> The student will be expected to
> 1) transpose the proof-of-concept changes made to JamVM and GNU
> Classpath into the OpenJDK x86 codebase (at least - ARM and
> additionally PowerPC would also be helpful)
> 2) clearly document all changes
> 2) ensure that the changed codebase passes any available and
> applicable unit tests, or come up with a test suite that ensures the
> changes are safe
> 3) provide example code for end users
> 4) benchmark performance improvements, and attempt additional
> optimizations in a separate patchset
> Naturally, since JamVM / Classpath and OpenJDK's codebase is quite
> dramatically different, the student will really only have a conceptual
> reference based on my original JamVM / Classpath proof-of-concept
> work.
> There are already people who have asked me to be their mentor for this
> task. I simply need the umbrella of an OpenJDK affiliated organization
> in order to complete my application.
> Many thanks in advance,
> Chris
> [1]
> [2]
> [3]

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