From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: Can we go GTK-only? Date: Tue, 01 Nov 2016 17:11:57 +0200 Message-ID: <83y413nsjm.fsf@gnu.org> References: <24db2975-17ca-ad01-20c8-df12071fa89a@dancol.org> <4615E73A-19E2-4B79-9889-D3FA686DDDE6@raeburn.org> <83bmy0pl8p.fsf@gnu.org> <831sywp7ew.fsf@gnu.org> Reply-To: Eli Zaretskii NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: blaine.gmane.org 1478013175 32218 195.159.176.226 (1 Nov 2016 15:12:55 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Tue, 1 Nov 2016 15:12:55 +0000 (UTC) Cc: raeburn@raeburn.org, monnier@iro.umontreal.ca, emacs-devel@gnu.org To: Daniel Colascione Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue Nov 01 16:12:51 2016 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1c1ajn-0005H5-4e for ged-emacs-devel@m.gmane.org; Tue, 01 Nov 2016 16:12:31 +0100 Original-Received: from localhost ([::1]:48397 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c1ajp-00069i-Sp for ged-emacs-devel@m.gmane.org; Tue, 01 Nov 2016 11:12:33 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:38436) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c1aj3-00068Z-4o for emacs-devel@gnu.org; Tue, 01 Nov 2016 11:11:46 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c1aiz-0007Yv-TK for emacs-devel@gnu.org; Tue, 01 Nov 2016 11:11:45 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:39524) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c1aiz-0007Yr-PX; Tue, 01 Nov 2016 11:11:41 -0400 Original-Received: from 84.94.185.246.cable.012.net.il ([84.94.185.246]:3928 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_128_CBC_SHA1:128) (Exim 4.82) (envelope-from ) id 1c1aiy-0007kC-Ru; Tue, 01 Nov 2016 11:11:41 -0400 In-reply-to: (message from Daniel Colascione on Mon, 31 Oct 2016 14:04:54 -0700) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:209059 Archived-At: > From: Daniel Colascione > Date: Mon, 31 Oct 2016 14:04:54 -0700 > Cc: Ken Raeburn , 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.