From: Daniel Colascione <dan.colascione@gmail.com>
To: Stefan Monnier <monnier@iro.umontreal.ca>
Cc: Andreas Schwab <schwab@linux-m68k.org>, Leo <sdl.web@gmail.com>,
emacs-devel@gnu.org
Subject: Re: How and when to use GCPRO?
Date: Mon, 27 Dec 2010 19:37:17 -0800 [thread overview]
Message-ID: <4D195B6D.2060305@gmail.com> (raw)
In-Reply-To: <jwvhbdyk5fs.fsf-monnier+emacs@gnu.org>
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On 12/27/10 6:17 PM, Stefan Monnier wrote:
>>>>> Actually, both Fcar and Fcdr can GC (by signalling an error which
>>>>> triggers the debugger).
>>>> But the debugger will not return.
>>> Oh, right,
>> Discussions like this worry me. What if the function is later changed to
>> call something that can GC? What if it's used in some new context? If
>> it's not utterly performance-critical code, isn't it better to be safe
>> than sorry and GCPRO anyway? It's not as if it's an expensive operation.
>> Premature optimization is the root of all evil, after all.
>
> On most platforms, GCPRO is a no-op, and on those where it's not, it's
> never been a major performance issue, AFAIK. The problem is just that
> it makes the code that much more verbose and painful to
> write/read/maintain.
Hrm. You learn something every day --- I thought Emacs was doing precise
GC the way it has since time immemorial. How much of a win was the
GC_MARK_STACK conservative scanning approach?
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next prev parent reply other threads:[~2010-12-28 3:37 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-27 9:21 How and when to use GCPRO? Leo
2010-12-27 10:15 ` Andreas Schwab
2010-12-27 10:38 ` Leo
2010-12-27 11:17 ` Andreas Schwab
2010-12-27 16:00 ` Stefan Monnier
2010-12-27 17:51 ` Andreas Schwab
2010-12-28 1:01 ` Stefan Monnier
2010-12-28 1:33 ` Daniel Colascione
2010-12-28 2:17 ` Stefan Monnier
2010-12-28 3:37 ` Daniel Colascione [this message]
2010-12-28 4:15 ` Stefan Monnier
2010-12-28 4:36 ` Conservative scanning (was: Re: How and when to use GCPRO?) Daniel Colascione
2010-12-28 17:07 ` How and when to use GCPRO? Richard Stallman
2010-12-27 19:15 ` Leo
2010-12-27 19:26 ` Common Lisp like feature expressions (was: How and when to use GCPRO?) Leo
2010-12-27 19:38 ` Andreas Schwab
2010-12-27 19:57 ` Leo
2010-12-28 1:01 ` Common Lisp like feature expressions Stefan Monnier
2010-12-28 15:26 ` Leo
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