From: Daniel Colascione <dancol@dancol.org>
To: Eli Zaretskii <eliz@gnu.org>, Paul Eggert <eggert@cs.ucla.edu>
Cc: raeburn@raeburn.org, monnier@iro.umontreal.ca, emacs-devel@gnu.org
Subject: Re: Can we go GTK-only?
Date: Tue, 1 Nov 2016 09:54:51 -0700 [thread overview]
Message-ID: <633d43c4-946e-e318-d8de-be1c2fde26f7@dancol.org> (raw)
In-Reply-To: <83lgx3no0k.fsf@gnu.org>
On 11/01/2016 09:49 AM, Eli Zaretskii wrote:
>> Cc: raeburn@raeburn.org, monnier@iro.umontreal.ca, emacs-devel@gnu.org
>> From: Paul Eggert <eggert@cs.ucla.edu>
>> Date: Tue, 1 Nov 2016 09:28:34 -0700
>>
>> On 11/01/2016 08:11 AM, Eli Zaretskii wrote:
>> > Only C11 mandates that malloc/realloc/free shall be thread-safe, and
>> we don't yet require C11.
>>
>> This is too pessimistic. C11 was the first C standard to talk about
>> threads, which is why it's the first C standard to specify whether
>> malloc is thread-safe. In practice it should be safe to assume that
>> malloc is thread-safe on multithreaded platforms, as C programmers would
>> have revolted en masse otherwise.
>
> "It should be safe" and "it's safe" are 2 different things.
>
>> > gmalloc is only thread-safe if Emacs is built with pthreads.
>>
>> Yes, and that's what one would expect. If you build Emacs in
>> single-threaded mode, malloc won't be thread-safe. But in the normal
>> case nowadays, malloc should be thread-safe.
>
> pthreads is not the only way to have threads.
On any modern system POSIX system it is. Counterexample, please.
>> > ralloc is not thread-safe at all.
>>
>> Yes, and ralloc as it stands should not be used on modern platforms. We
>> clearly need to move in that direction anyway.
>
> We do move in that direction, but we aren't there yet.
>
>> > xmalloc calls memory_full, which manipulates global state and calls
>> xsignal, so that is not thread-safe, either.
>>
>> That's fine, so long as xmalloc is called only in the Emacs Lisp thread.
>
> I'd imagine any code that wants to allocate from the heap will call
> xmalloc, as we never call malloc directly in Emacs AFAIK.
That's because we want xmalloc to handle memory exhaustion in a sane
way. A thread calling system malloc on its own can handle memory
exhaustion a different way. Memory exhaustion being reported in some way
is what really matters.
> Like I said: we are barely out of the woods, so allocations from the
> heap in non-main threads should be avoided.
This restriction makes a big class of programs very difficult to write.
Besides, in my Emacs right now, I have in addition to the main thread a
generic glib worker thread, a dconf worker thread, and a gdbus thread.
I'd be amazed if none of these threads allocated memory.
next prev parent reply other threads:[~2016-11-01 16:54 UTC|newest]
Thread overview: 85+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-27 19:54 Can we go GTK-only? Daniel Colascione
2016-10-27 20:05 ` Frank Haun
2016-10-27 20:45 ` Daniel Colascione
2016-10-27 21:08 ` Frank Haun
2016-10-27 20:32 ` Paul Eggert
2016-10-27 23:15 ` Perry E. Metzger
2016-10-28 7:13 ` Eli Zaretskii
2016-10-28 2:35 ` Richard Stallman
2016-10-28 6:22 ` Eli Zaretskii
2016-10-28 7:27 ` Ulrich Mueller
2016-10-28 8:15 ` Eli Zaretskii
2016-10-28 10:48 ` Frank Haun
2016-10-28 12:26 ` Eli Zaretskii
2016-10-28 13:35 ` Stefan Monnier
2016-10-30 14:43 ` Ken Raeburn
2016-10-30 21:42 ` Stefan Monnier
2016-10-30 22:49 ` Daniel Colascione
2016-10-30 23:57 ` Stefan Monnier
2016-10-31 3:37 ` Eli Zaretskii
2016-10-31 15:57 ` Eli Zaretskii
2016-10-31 0:00 ` YAMAMOTO Mitsuharu
2016-10-31 8:24 ` Ken Raeburn
2016-10-31 16:34 ` Perry E. Metzger
2016-11-01 8:22 ` YAMAMOTO Mitsuharu
2016-10-31 3:33 ` Eli Zaretskii
2016-10-31 15:57 ` Perry E. Metzger
2016-10-31 15:56 ` Eli Zaretskii
2016-10-31 15:59 ` Daniel Colascione
2016-10-31 16:47 ` Eli Zaretskii
2016-10-31 17:54 ` Perry E. Metzger
2016-10-31 20:50 ` Eli Zaretskii
2016-10-31 15:52 ` Eli Zaretskii
2016-10-31 15:54 ` Eli Zaretskii
2016-10-31 18:22 ` Ken Raeburn
2016-10-31 20:53 ` Eli Zaretskii
2016-10-31 21:04 ` Daniel Colascione
2016-11-01 15:11 ` Eli Zaretskii
2016-11-01 16:28 ` Paul Eggert
2016-11-01 16:49 ` Eli Zaretskii
2016-11-01 16:54 ` Daniel Colascione [this message]
2016-11-01 17:08 ` Eli Zaretskii
2016-11-01 17:16 ` Daniel Colascione
2016-11-01 19:15 ` Perry E. Metzger
2016-11-01 19:28 ` Lars Ingebrigtsen
2016-11-01 19:31 ` Eli Zaretskii
2016-11-01 16:55 ` Paul Eggert
2016-11-01 17:15 ` Perry E. Metzger
2016-11-01 16:41 ` Perry E. Metzger
2016-11-01 16:54 ` Eli Zaretskii
2016-11-01 17:22 ` Perry E. Metzger
2016-11-01 17:46 ` Eli Zaretskii
2016-11-01 17:56 ` Perry E. Metzger
2016-11-01 19:35 ` Perry E. Metzger
2016-11-01 16:45 ` Daniel Colascione
2016-11-01 17:01 ` Eli Zaretskii
2016-11-01 17:06 ` Daniel Colascione
2016-11-01 17:15 ` Eli Zaretskii
2016-11-01 17:18 ` Daniel Colascione
2016-11-01 17:44 ` Eli Zaretskii
2016-11-01 17:45 ` Daniel Colascione
2016-11-01 19:14 ` Stefan Monnier
2016-11-01 19:22 ` Eli Zaretskii
2016-11-01 19:42 ` Perry E. Metzger
2016-11-01 19:20 ` Perry E. Metzger
2016-11-01 20:05 ` Eli Zaretskii
2016-11-01 20:17 ` Daniel Colascione
2016-11-01 20:42 ` Eli Zaretskii
2016-11-02 2:26 ` Perry E. Metzger
2016-11-02 15:49 ` Eli Zaretskii
2016-11-02 15:55 ` Daniel Colascione
2016-11-02 5:00 ` YAMAMOTO Mitsuharu
2016-11-02 15:46 ` Eli Zaretskii
2016-11-03 3:43 ` YAMAMOTO Mitsuharu
2016-11-03 17:40 ` Eli Zaretskii
2016-11-02 0:27 ` Stefan Monnier
2016-11-02 15:53 ` Eli Zaretskii
2016-11-02 16:04 ` Stefan Monnier
2016-11-02 19:25 ` Nikolaus Rath
2016-11-02 19:25 ` Nikolaus Rath
2016-11-02 20:33 ` Paul Eggert
2016-11-03 1:25 ` Richard Stallman
2016-11-02 20:13 ` Eli Zaretskii
2016-11-03 3:29 ` Perry E. Metzger
2016-11-03 18:07 ` John Wiegley
2016-11-03 22:07 ` John Wiegley
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