> > I wish to read the algorithm of gc, and I cannot.
>
> The Emacs gc is a simple mark and sweep collector.

Right.

Alin, you can start by reading the node "Garbage Collection" in the
ELisp manual, and then proceed reading alloc.c, where you will see
many functions named mark_SOMETHING and then gc_sweep that does the
sweep stage. If you want more background before reading the ELisp
manual, try googling "mark and sweep garbage collection".

I have read the mark-sweep algorithm; I know it. However, I do not manage making the connection with alloc.c.

For example, I cannot understand what kind of objects are kept in every node of the red-black tree (in books I never saw gc implemented with red-black trees). I know that the objects are kept in obarrays. What link is there between obarrays and red-black tree of gc ?

What happens to a Lisp_Object defined in C code? Is it freed if it is found by conservative stack algorithm ? What is the link between GCPRO? macros and the gc ?