On Mon, Apr 17, 2023 at 08:44:51PM +0200, Bruno Haible via Cygwin wrote:
> Btw, there are two more functions in the posix_spawn family meanwhile:
> * posix_spawn_file_actions_addchdir_np
> implemented by glibc [1], musl libc, macOS, FreeBSD [2], Solaris ≥ 11.3
> used by a few packages (Firefox, Chromium, Rust)
> * posix_spawn_file_actions_addfchdir_np
> implemented in glibc, musl libc
> but not used by any package so far [3].
>
> The next POSIX will contain these functions (without the _np suffix).[4]
>
> Bruno
>
> [1] https://sourceware.org/bugzilla/show_bug.cgi?id=17405
> [2]
> https://man.freebsd.org/cgi/man.cgi?query=posix_spawn_file_actions_adddup2&apropos=0&sektion=3&manpath=FreeBSD+11-current&format=html
> [3] https://codesearch.debian.net/
> [4] https://www.austingroupbugs.net/view.php?id=1208
With regards to [3] above, the next lighttpd release (lighttpd 1.4.70)
will use posix_spawn_file_actions_addfchdir_np(), where available, for
spawning CGI programs.
I have not yet tested under cygwin, but under Linux the overhead of
initial CGI process creation can be greatly reduced by using
posix_spawn() instead of fork(),execve(). The speedup is inversely
proportional to how much work the target script performs (compared to
the overhead of initial process creation). On x86_64 Linux, running a
minimal C program for CGI can be ~60% faster in lighttpd when using
posix_spawn()! When running a minimal /bin/sh program for CGI, the
speedup is "only" ~20%! (Those numbers were obtained from running
h2load and weighttp microbenchmarks with the minimal CGI programs.)
minimal C program for CGI (compiled gcc -O3):
#include <unistd.h>
static const char resp[] = "Status: 200\n\n";
int main(void) { write(STDOUT_FILENO, resp, sizeof(resp)-1); return 0; }
minimal /bin/sh program for CGI:
#!/bin/sh
printf 'Status: 200\n\n'
Cheers, Glenn
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