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Escape analysis and stack allocation

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jurna
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Joined: 2005-06-26
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Hello.

I's been quite a lot of posts on the net about Mustang's escape analysis and stack allocation capabilities. But recently I can't find any progress on that topic. I know that escape analysis is already performed, but stack allocation is not implemented yet.

Is this feature still planned for Mustang?

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atripp
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Joined: 2003-07-15
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> Thanks for the info. I might be willing to invest
> some time improving the JDK source, iff it was
> released under an open source license (approved by
> www.opensource.org). Current licenses are too
> restrictive (for example modifications released under
> JRL can only be used for research purposes).

Correct me if I'm wrong, but the JRL just says that you can't release your own JDK/JVM on your own, except for research purposes. You can certainly make an enhancement, submit it to Sun, and then get the enhancement (along with everyone else) as part of Sun's JDK/JVM. Yes, you'll have to wait longer, but that's the price we pay for extensive review and testing.

mayhem
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Joined: 2003-06-11
Points: 0

> Correct me if I'm wrong, but the JRL just says that
> you can't release your own JDK/JVM on your own,
> except for research purposes. You can certainly make
> an enhancement, submit it to Sun, and then get the
> enhancement (along with everyone else) as part of
> Sun's JDK/JVM.

Yes, of course. Sun accepts patches. You automatically own any code you create, Sun can't change that in a license.

> Yes, you'll have to wait longer, but
> that's the price we pay for extensive review and
> testing.

"the price we pay"?? I don't see how Sun accepting patches has anything to do with open sourcing Java. But as I wrote before, this is another topic.

mayhem
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Joined: 2003-06-11
Points: 0

> no it has been assigned to Dolphin, as all the other
> 50% really throughbreaking features.
> I think at least 50% wont make it to Dolphin too :-(

Agreed. It seems all "hard" problems are pushed ahead to the next release again and again. Maybe Sun don't have the skills and knowledge to fix them, or maybe their priorities are way off. My top 3 list of major problems with Java is:

1. Memory usage. GC pauses are still a problem, heap size is a problem. And no, adding a few command line arguments to the JVM is not a solution. It should just work out of the box. Why should I need to specify min/max heap size? Ridiculous.

2. Object allocation. Sun claims heap allocation is virtually free, well, it's not. Stack allocation would boost performance an order of magnitude for some applications, and it would enable much cleaner code solutions in many areas.

3. JRE bloat. Why add everything and its horse in the JRE libraries? The JRE is getting bigger and bigger with every release. Java needs a well-designed package system with versioning and dependency information.

Honestly, with the current progress, I don't see any of these problems being solved in the near future, if ever.

kamg
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Joined: 2005-06-16
Points: 0

Hi mayhem,

The sources for Hotspot are available just as the rest of the JDK. If you've got the skills and motivation, I'm sure the Hotspot engineers would welcome your help! Go over to http://java.sun.com/developer/technicalArticles/J2SE/peabody/
for instructions on how to get started. Every little bit helps!

mayhem
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Joined: 2003-06-11
Points: 0

Thanks for the info. I might be willing to invest some time improving the JDK source, iff it was released under an open source license (approved by www.opensource.org). Current licenses are too restrictive (for example modifications released under JRL can only be used for research purposes). But that's another topic.

Maybe what I'm missing is some kind of development plan. Which features/bugs are you working on? Which features are planned and when are they planned on being implemented? A time plan for each JRE module (Hotspot, Swing etc.) would be great.

kamg
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Joined: 2005-06-16
Points: 0

Hi mayhem -

I'm not sure exactly what you're looking for (and I'm sure I wouldn't know the answers even if so), but there's a mustang project page here that has a bit of info on the features/status of the project: https://mustang.dev.java.net/

Also, I'll bet there are some blogs at http://blogs.sun.com that have some more detailed information about some of the projects - and you might be able to even converse via the comments with the engineer.

Yeah, the license issues might be unfortunate. But I think Sun's heading in the right direction here becoming more and more open and who knows what the future will bring. Any improvements to the VM/JDK even in it's current form would still have the effect of helping out lots of people that use/develop Java. Many of the other JDKs out there use the code that Sun provides, so improvements here may help move them along as well.

robilad
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Joined: 2004-05-05
Points: 0

None of the open source VMs can use Sun's code though, so contributing to Sun's proprietary code base seems to be less useful than contributing to an open source one, if your argument is about largest usefulness of a contribution in terms of possible users.

After all, Sun can use open source code in Mistang (and they do), it's just forbidden by Sun to do it the other way round with Sun's proprietary code.

cheers,
dalibor topic

trembovetski
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Joined: 2003-12-31
Points: 0

> .. if your argument is about largest usefulness of a contribution in terms of possible users.

I guess that's debatable: by contributing to Sun
implementation one would arguably help much larger number of
users since I believe the number of people using Sun vm is
quite a bit larger than any open source jvms.

Thanks,
Dmitri
Java2D Team

alexlamsl
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Joined: 2004-09-02
Points: 0

> I guess that's debatable: by contributing to Sun
> implementation one would arguably help much larger
> number of
> users since I believe the number of people using Sun
> vm is
> quite a bit larger than any open source jvms.

+1 on that - it is at least an order of magnitude more useful :D

linuxhippy
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Joined: 2004-01-07
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no it has been assigned to Dolphin, as all the other 50% really throughbreaking features.
I think at least 50% wont make it to Dolphin too :-(

rvprasad
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Joined: 2005-01-09
Points: 0

Out of curiousity, is there a list of "throughbreaking" features that will make into Mustang or postponed to Dolphin? If so, can the public access this list?