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From: Philipp
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Subject: Re: master 2c79a8f 2/2: Use posix_spawn if possible.
Date: Tue, 9 Nov 2021 15:46:45 +0100
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Cc: Eli Zaretskii , Alan Third ,
YAMAMOTO Mitsuharu ,
Emacs developers
To: Aaron Jensen
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> Am 08.11.2021 um 12:00 schrieb Aaron Jensen :
>=20
> Hi all,
>=20
> Attached is the posix spawn patch adapted to be only effective on
> Darwin. I chose to leave the patch as-is aside from adding the
> additional conditional, but let me know if I should do something
> different. It wasn't clear where things stood in terms of whether or
> not we would ever want to use posix_spawn on non-darwin OSes.
I guess either way is fine. I'd slightly lean towards enabling it =
whenever it's available (i.e. remove the condition on DARWIN_OS):
1. The libc implementation of posix_spawn can make use of =
system-specific implementation improvements. For example, GNU libc on =
GNU/Linux uses the `clone' system call instead of `vfork' to create a =
separate stack for the subprocess.
2. Since it's easier to run a continuous integration suite on free OSes, =
by exercising the posix_spawn code path on them we can improve test =
coverage.
3. Using posix_spawn is simpler since it's not possible to accidentally =
introduce undefined behavior (by calling an async-signal-unsafe function =
in the child).
My original motivation for dropping the posix_spawn branch was that =
we'll have to maintain the fork/exec branch for the foreseeable future =
and that there's no measurable benefit from using posix_spawn, so it =
would just be additional code to maintain. Since that argument is no =
longer correct, we might as well use posix_spawn where possible.=