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From: ceb@csli.Stanford.EDU (Charles Buckley)
Newsgroups: comp.lang.lisp
Subject: Re: Is this the end of the lisp wave?
Message-ID: <17418@csli.Stanford.EDU>
Date: 24 Jan 91 16:32:03 GMT
References: <NETMAILR11011708110SEB1525@MVS.DRAPER.COM> <17374@csli.Stanford.EDU> <1991Jan23.080259.19816@Think.COM>
Organization: Center for the Study of Language and Information, Stanford U.
Lines: 35
In-reply-to: barmar@think.com's message of 23 Jan 91 08:02:59 GMT

In article <1991Jan23.080259.19816@Think.COM> Barry Margolin writes:
   In article <17374@csli.Stanford.EDU> Charles Buckley writes:
   >Exact.  Makes prototyping a breeze.  However, I'd still like to do my
   >own storage management in Lisp when my algorithm makes that possible
   >and expedient.  It's simply not provided for in CL.

   I'm not sure precisely what type of extension you're referring to.  Both
   Symbolics and Lucid provide "resources", which are pools of objects that
   can be reused rather than consing new objects each time

But resources are nothing more than a sort of software cache of
currently unused objects belonging to an isomorphic class.  If you
will, it's a sort of pointer-in-reserve system, to assure that that
which you allocated and might need again doesn't get eaten up
unnecessarily by the gc, just because you don't happen to have
explicitly programmed full pointer coverage for the life of your
algorithm.  It's nothing more than a slickered-up version of the hack
that Doug Cutting replied with.

Calling clear-resource only removes all these pointers-in-reserve,
*allowing* the gc to find the freed storage in the course of its own
plodding, methodical ruminations --- this according to language in the
vendor doc, and from my conversation with one of its employees who
should know.  If I turn the gc off, calling clear-resource does me no
good - memory still gets exhausted.  In those circumstances in which
gc performance is pathologically poor, the resource facility does
nothing to offload it.

I want to be able to tell the gc "I'll let you know when I'm done with
memory, and you should manage the free chunks, consolidating and all
that, but don't bother hunting through memory for non-referenced
blocks."  So the above-referenced employee: "That that would
make gc design too hard."

Well, C runtime supports it . . .