On Wed, 6 Mar 2024 at 01:08, Mark Geisert via Cygwin <cygwin@cygwin.com> wrote: > > On 3/5/2024 2:42 PM, Dan Shelton via Cygwin wrote: > > On Mon, 4 Mar 2024 at 07:45, Mark Geisert via Cygwin <cygwin@cygwin.com> > > wrote: > >> > >> On 3/3/2024 7:27 PM, Dan Shelton via Cygwin wrote: > [...] > >>> strace does not help, as I need the Win32 calls BELOW posix_spawn(), > >>> to see the implementation details. > >> > >> Check the source code, then. It's at: > >> https://cygwin.com/cgit/newlib-cygwin/tree/winsup/cygwin/fork.cc > >> > >> Look at line 587; there's the static function dofork(). Look at the > >> thirty or so lines above that; there's both fork() and > >> __posix_spawn_fork() calling dofork(). So both those user-level > >> functions call into the exact same internals. (BTW __posix_spawn_fork() > >> is called from posix_spawn(); the latter is in newlib and not Cygwin.) > >> > >> You can even see the reason it's done this way by reading the comment. > > > > Yes, but it is as I feared, Cygwin posix_spawn() does not use Win32 > > spawn() at all, and instead uses a rather inefficient vfork() > > solution. > > Cygwin's vfork() is just a wrapper around fork(), so yes. But anyway... > > > posix_spawn() was added to POSIX so a Win32 implementation can use Win32 > > spawn() > > ...now I see what you're getting at: > > If posix_spawn() is intended to launch truly unrelated processes, with > minimal or no coordination with the launching process, why can't it just > use Windows' CreateProcess? I assume here that's what Win32 spawn() does. >
I'm not sure, but I think this would benefit Cygwin greatly to implement a native posix_spawn(). It should be faster and scale better. Also the only stuff which do really need fork() are bash/dash/ksh, and maybe daemon stuff like sshd. Re CreateProcess: Maybe CreateProcess() breaks access token or newgrp support? Does Cygwin do bounties (paid bug fixes), or Google Summer Of Code? Dan -- Dan Shelton - Cluster Specialist Win/Lin/Bsd -- Problem reports: https://cygwin.com/problems.html FAQ: https://cygwin.com/faq/ Documentation: https://cygwin.com/docs.html Unsubscribe info: https://cygwin.com/ml/#unsubscribe-simple
