Re: [PATCH 2/2] job.c: implementing child_execute_job() using posix_spawn(), and use it if present

[Barath Aron]

On 07/30/2018 12:21 PM, Paul Smith wrote:
> This weekend I reworked the handling of failures in child_execute_job()
> so that it behaves properly even when the child failure happens in the
> current process (e.g., the fork() or posix_spawn()).
>
> It needs a bit of cleanup--in particular writing a test is complicated
> by the fact that errors currently have different formats when built
> with fork() vs. posix_spawn().  I need to decide if I want to align
> them or fix the test to understand the difference.
>
> I also added a configure --disable-posix-spawn option for those who
> want to continue to use fork()/vfork() even when posix_spawn() is
> available.
Perfect. I can't wait to try it. :)
>   Since there's one missing bit of functionality in the
> posix_spawn() case (resetting the stack size in the child) and I don't
> think that using posix_spawn() buys you much if anything over vfork()
> in GNU/Linux, at least.
Yeah, that stuff is missing. The specification [1] does not tell 
anything about the stack size (and limits in general), but I think I 
read in some manual that limits will not be reset.
So the only possible implementation will be reset the stack in the 
current process, spawn, and set the stack size again. Which sounds quite 
odd to me, thus I didn't implemented this.

[1] 
http://pubs.opengroup.org/onlinepubs/9699919799/functions/posix_spawn.html