[PATCH] libfortran/90038: Use posix_spawn instead of fork

[Janne Blomqvist]

On Thu, May 16, 2019 at 10:59 PM Thomas Koenig <tkoenig@netcologne.de> wrote:
>
> Hi Janne,
>
> > fork() semantics can be problematic.  Most unix style OS'es have
> > posix_spawn which can be used to replace fork + exec in many cases.
> > For more information see
> > e.g. https://www.microsoft.com/en-us/research/uploads/prod/2019/04/fork-hotos19.pdf
> >
> > This replaces the one use of fork in libgfortran with posix_spawn.
>
> Do I understand the patch correctly that we would no longer use fork()
> if posix_spawn is not available?  I think we should leave that in as
> a fallback option.

Yes. But there is already a fallback in case posix_spawn (or
previously, fork) is not available, namely falling back to synchronous
behavior. Since this is anyway somewhat of a corner case (namely, with
wait=.false.), and posix_spawn is supported on all (well, at least
Linux, macOS, *BSD, cygwin, Solarix, AIX) remotely modern unix type
systems, a further fallback to fork() is IMHO not warranted.


-- 
Janne Blomqvist