From: Eli Zaretskii <eliz@gnu.org>
To: Daniel Colascione <dancol@dancol.org>
Cc: raeburn@raeburn.org, monnier@iro.umontreal.ca, emacs-devel@gnu.org
Subject: Re: Can we go GTK-only?
Date: Tue, 01 Nov 2016 17:11:57 +0200 [thread overview]
Message-ID: <83y413nsjm.fsf@gnu.org> (raw)
In-Reply-To: <r025vaw8b56x.fsf@dancol.org> (message from Daniel Colascione on Mon, 31 Oct 2016 14:04:54 -0700)
> From: Daniel Colascione <dancol@dancol.org>
> Date: Mon, 31 Oct 2016 14:04:54 -0700
> Cc: Ken Raeburn <raeburn@raeburn.org>, monnier@iro.umontreal.ca,
> emacs-devel@gnu.org
>
> >> > One problem with
> >> > having too much code in separate threads is that only the main thread
> >> > can call malloc/free, i.e. you cannot create/destroy objects in other
> >> > threads.
> >>
> [...]
> Of course you can call malloc from multiple threads. Otherwise, projects
> like jemalloc would be pointless. You can freely allocate and deallocate
> from different threads on both POSIX and Windows systems, and there is
> no need to free an object on the thread that allocated it.
IMO, this is not a safe assumption, even though in practice more and
more systems out there provide thread-safe native malloc. Only C11
mandates that malloc/realloc/free shall be thread-safe, and we don't
yet require C11. gmalloc is only thread-safe if Emacs is built with
pthreads. ralloc is not thread-safe at all. xmalloc calls
memory_full, which manipulates global state and calls xsignal, so that
is not thread-safe, either.
IOW, we are barely out of the woods with thread-safety of memory
allocation, so IMO it's too early for us to build basic infrastructure
on the thread-safety assumption. For experimental and exotic
features, yes, but not for something that must work well on all
supported systems.
> >> Creating Lisp objects, that’d be another matter, unless locking is
> >> introduced to the allocator.
> >
> > If you cannot allocate Lisp objects, the scope of what you can do in
> > the non-main threads is greatly diminished. E.g., no computation
> > intensive jobs that operate on buffer text can be off-loaded to other
> > threads.
>
> Allocation of lisp objects is different. _That_ isn't thread safe
> right now. The easiest way to address this problem is a GIL.
GIL hurts performance so much that I'd question any GIL-based design
that attempts to support off-loading CPU-intensive tasks to worker
threads.
next prev parent reply other threads:[~2016-11-01 15:11 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 [this message]
2016-11-01 16:28 ` Paul Eggert
2016-11-01 16:49 ` Eli Zaretskii
2016-11-01 16:54 ` Daniel Colascione
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 20:33 ` Paul Eggert
2016-11-03 1:25 ` Richard Stallman
2016-11-02 19:25 ` Nikolaus Rath
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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