Dear all, I will make a better implementation at image side, and cover everything with comments, as Eliot suggested. On 20 May 2010 22:23, Stéphane Ducasse <stephane.ducasse@inria.fr> wrote:

igor

I have a question about your new finalization. Can we add it to Pharo?

yes, you can. But without VM modifications it won't work. That's why i postponed image-side integration for a better time(s). Old images, how Chris already mentioned, don't need to be aware of changes on VM side and will continue to function as if nothing happen.

Should we replace something else (I mean it is something to replace an existing solution).

Well, it works best if you having a lot of weak refs, while only few of them dying time to time. You are free to implement a post-mortem action however you like (but this is also true for current implementation, except that new scheme is much more effective).

How does it interact with existing code?

I will replace an existing WeakRegistry, which will work exactly as an old one. Also, if you want, i can add a fallback mechanism, if you will run your image using older VM. Any other uses of new finalization is up to you :) As you may guess, a Magma exploits new finalization enhancement for own needs. For this, I implemented a specialized weak dictionaries, which clean themselves automatically (Magma don't needs to deal with finalization of objects, it just needs to keep buffers free of garbage). This was a real-world use of new features, which shown us its benefits. Thanks to Cris for taking care integrating and testing it.

You see I will learn a lot again :)

Stef

...

From: "David T. Lewis" <lewis@mail.msen.com> Date: May 20, 2010 5:59:07 PM GMT+02:00 To: ma.chris.m@gmail.com, The general-purpose Squeak developers list <squeak-dev@lists.squeakfoundation.org> Cc: vm-dev@lists.squeakfoundation.org Subject: Re: [squeak-dev] Finalization enhancement for 4.2 Reply-To: The general-purpose Squeak developers list <squeak-dev@lists.squeakfoundation.org>

CC to vm-dev list, follow up on technical issues should go to vm-dev.

Chris, Igor, this sounds very encouraging. Yes, I'll help on the VM side, with guidance from Andreas and others (I am not technically competent on this issue). I'll probably be off list for a few days, but will catch up on this next week.

Andreas, Eliot, others - any advice or guidance?

Dave

On Thu, May 20, 2010 at 10:14:00AM -0500, Chris Muller wrote:

...

I have packaged up Igor's change-sets for the finalization fix:

 http://bugs.squeak.org/view.php?id=7525  http://bugs.squeak.org/view.php?id=7473

into their respective MC packages and uploaded them to the Inbox.

Recall the original discussion:

 http://lists.squeakfoundation.org/pipermail/vm-dev/2010-March/003958.html

I have been running with Igor's enhanced VM and image-side finalization patches for a few weeks now.  The results are striking. Squeak applications using large Weak-collections deteriorate to a point of unusability without this fix because Squeak spends 95% of its time in the finalization process, leaving no time for application processing. With this fix installed, CPU utilization is 0% when the application is idle, providing excellent responsiveness.

This is a big, big, win for any application that uses Weak collections, and a win for Squeak overall because it's own use of weak-collections is enhanced.

While it seems to be backward compatible, e.g. I am able to run the enhanced VM on older images (including 3.9), and I am able to run with these image changes on an older VM, both are required to take advantage of the enhanced finalization.

I would like to push this into the trunk, but will need help from the VMMaker developers for that piece.  David?

For Magma, this wil be the most exciting and important fix since #becomeForward:copyHash: introduced back in 2004.

- Chris

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-- Best regards, Igor Stasenko AKA sig.