Re: Calling scheme from C: problem with GC.

[Martin Grabmueller]

> From: Rob Browning <address@hidden>
> Date: Mon, 26 Nov 2001 15:23:31 -0600
> 
> Chris Cramer <address@hidden> writes:
> 
> > I think what you need is scm_gc_protect_object(). It takes one argument,
> > the object you want to protect from garbage collection. Unprotect it with
> > scm_gc_unprotect_object(). If you want to protect multiple objects, it
> > may be a better idea to place them in a vector or list and then protect
> > that (since protecting an object also protects everything it references).
> 
> I've seen this suggested in a number of places, but what's the harm in
> just always using scm_protect/unprotect_object.  Is there some
> performance penalty or similar if you're using it for a large number
> of items?

IIRC, scm_protect/scm_unprotect put their argument into a hash table
and delete it from a hash table, so each time one of them is called, a
table search happens.  Putting references into a vector or list avoids
this.  Even better are the new mechanisms for registering GC roots,
though the new function names have slipped my mind...

'martin