On Mon, Jul 19, 2010 at 6:16 AM, Mariano Martinez Peck <marianopeck@gmail.com> wrote:

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Hi. Nebwie here. THe first question is if objects are moved (changed the address in memory) at runtime?�

yes.

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I am 99% sure the answer is true. If so:

1) Who moves them ? the GC?

yes.

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2) when ?� agains which events, what triggers these movements?

during garbage collection

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3) why they are moved?� to compact the memory ?� why the memory needs to be compact? for arrays?

In Squeak's case to compact memory. �But scavenging/two-space-collection is a widely used technique that works by copying the live objects from one space into another, com[acting as it goes, and so it is expected with modern algorithms that memory is compacted as garbage is collected. �See Paul Wilson's�Uniprocessor Garbage Collection Techniques.

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4) Is there a way to say "please, don't move this object X" ?� what would be the problem of having a lot of these "non-moveable" objects? memory fragmentation ?

Not yet. �I'm working on it for Teleplace's threaded Cog VM.

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If you can point me to the code also I would be happy.

See the garbage collection and gc protocols in ObjectMemory and (in Cog) NewObjectMemory in VMMaker.

Thank you very much in advance,

Mariano

HTH

Eliot�