Re: master 4ac4cec652f: Prevent freezes on macOS (bug#69561)

[Po Lu]

Gerd Moellmann <gerd@gnu.org> writes:

>    if (NSApp == nil
>        || ![NSThread isMainThread]
>        || (timeout && timeout->tv_sec == 0 && timeout->tv_nsec == 0))
> -    return thread_select (pselect, nfds, readfds, writefds,
> -                       exceptfds, timeout, sigmask);
> +    thread_select (pselect, nfds, readfds, writefds,
> +                exceptfds, timeout, sigmask);

Far be it from me to offer advice on code I know very little about, but
on the surface this appears to force non-main threads to enter [NSApp
run] whenever they enter select.  Is this really the desired behavior?

I should think that this function, being provided by the toolkit for the
purpose of running its event loop, must be called by strictly one thread
at a time.