Michael Neumann
1/9/2005 8:35:00 PM
Lothar Scholz wrote:
> Hello Michael,
>
> MN> Martin Pirker wrote:
>
>>>"Eustáquio Rangel de Oliveira Jr." <eustaquiorangel@yahoo.com> wrote:
>>>
>>>
>>>>And, do you have some links about the the Ruby mark-and-sweep type of
>>>>garbage?
>>>
>>>
>>>While I lack the skill to go source diving, I too am interested in more
>>>info about the gc.
>>>We use conservative gc [talk:102873], ok
>>>
>>>So, can one help gc?
>>>e.g. if an Array or Hash is no longer needed, does an Array.clear or
>>>Hash.clear actually zero all internal pointers to help/speed up gc?
>
>
> MN> Yes, that should help, as the mark function would no more mark all the
> MN> value. But I doubt that would be much of a performance win, because if
> MN> the array-object goes out of scope (it's no more reachable), it's mark
> MN> function would no longer be called. So, you would not want to call
> MN> #clear. But that's just my understanding...
>
> This would only help if there is something on the stack that looks
> like an address to this array object. The chance for this is very low
> and so the performance win. With the Boehm-Weisser GC i a measurable
> memory reduction (~20%) by doing this for eiffel. But Boehm-Weisser
> scans everything conservative and not only the heap like ruby.
Hm, my understanding of Ruby's GC is that it scans the stack
conservative (meaning that all values on the stack that look like
references to memory are handled as references), but not the heap (how
could you conservativly scan the heap?). But probably I misunderstood you.
And my final conclusion was that it does not help much, if any, despite
my initial "Yes" ;-)
Regards,
Michael