ANN: Dogelog Runtime, Prolog to the Moon (2021)

[Mostowski Collapse]

I am refering to:

Greg Ewing schrieb:
 > where [w] is a weak reference object. Then you could periodically
 > scan the trail looking for dead weakref objects and remove the
 > corresponding [*] node from the list.
 >
 > You can also attach callbacks to weakref objects that are triggered
 > when the referenced object dies. You might be able to make use of
 > that to remove items from the trail instead of the periodic scanning.

Question to Chris Angelico: If I stay with my
sweep_trail(), which is the periodically scanning,
I can use a single linked list.

On the other hand if I would use the trigger
from Python, I possibly would need a double linked
list, to remove an element.

Chris Angelico, is there a third option, that I have
overlooked? Single linked list uses less space
than double linked list, this why I go with scan.

Chris Angelico schrieb:
> On Sun, Sep 19, 2021 at 11:46 AM Mostowski Collapse <bursejan at gmail.com> wrote:
>>
>> Yeah, it seems weak references could indeed spare
>> me mark_term(). But then I am stil left with sweep_trail().
>> I did not yet measure what takes more time mark_term()
>> or sweep_trail(). The displayed "gc" is the sum of both.
>>
>>  From what I have seen, very large trail practically reduced
>> to a zero trail during Prolog GC, I am assuming that
>> mark_term() is not the working horse. Usually mark_term()
>> only marks what is not-Garbage, and sweep_trail()
>>
>> has to deal with Garbage and not-Garbage. And there
>> is usually a lot of Garbage, much more than not-Garbage.
>> Finding the objects that survive, is like finding the needle
>> in the haystack, except we do not have to scan the
> 
> If you stop referring to something, it is garbage. Python will dispose of it.
> 
> You literally need to do nothing at all, and let the language take
> care of things.
> 
> ChrisA
>