Re: Can we go GTK-only?

[YAMAMOTO Mitsuharu <mituharu@math.s.chiba-u.ac.jp>]

>>>>> On Tue, 01 Nov 2016 22:42:27 +0200, Eli Zaretskii <eliz@gnu.org> said:

>> Emacs today can tolerate arbitrary memory allocations off the main
>> thread after dumping using the system heap. I know this to be case
>> because Emacs today, on the most common platforms --- OS X,
>> GNU/Linux, and Windows, all perform allocations off the main thread
>> in very common configurations _already_.

> The only platform I know about that starts non-main threads which
> run Emacs application code is MS-Windows, and there we don't
> allocate anything off the heap, at least not off the same heap that
> is used by the main (Lisp) thread.

The font backend driver macfont.m imported from the Mac port does
deallocation off the main thread for some data that were allocated in
the main thread.

  1489	              dispatch_group_async (group, queue, ^{
  1490	                  int nkeys;
  1491	                  uintptr_t key;
  1492	                  nkeys = nkeys_or_perm;
  1493	                  for (key = row * (256 / NGLYPHS_IN_VALUE); ; key++)
  1494	                    if (CFDictionaryContainsKey (dictionary,
  1495	                                                 (const void *) key))
  1496	                      {
  1497	                        CFDictionaryRemoveValue (dictionary,
  1498	                                                 (const void *) key);
  1499	                        if (--nkeys == 0)
  1500	                          break;
  1501	                      }
  1502	                });

I can disable this for NS if it does not fit with the current policy
of GNU Emacs mainline source code.
(You can find more use cases of threads via libdispatch in the Mac
port.  Even basic drawings are done off the main thread.)

Of course, external libraries would do memory allocation/deallocation
across the threads behind the scenes.

				     YAMAMOTO Mitsuharu
				mituharu@math.s.chiba-u.ac.jp