Re: Can we go GTK-only?

[Paul Eggert]

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.

> 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.

> 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.

> 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. 
xmalloc is like xsignal, Fcons, and lots of other functions that should 
be called only in the Emacs Lisp thread.