On Wed, Aug 30, 2023 at 09:48:42AM +1200, Thomas Munro wrote:
> On Wed, Aug 30, 2023 at 1:49 AM Noah Misch <n...@leadboat.com> wrote:
> > On Tue, Aug 29, 2023 at 04:25:24PM +1200, Thomas Munro wrote:
> > > On Tue, Aug 29, 2023 at 1:48 PM Noah Misch <n...@leadboat.com> wrote:
> > > > https://github.com/cpan-authors/IPC-Run/issues/166#issuecomment-1288190929
> > >
> > > Interesting. But that shows a case with no pipes connected, using
> > > select() as a dumb sleep and ignoring SIGCHLD. In our usage we have
> > > pipes connected, and I think select() should return when the child's
> > > output pipes become readable due to EOF. I guess something about that
> > > might be b0rked on Windows? I see there is an extra helper process
> > > doing socket<->pipe conversion (hah, that explains an extra ~10ms at
> > > the start in my timestamps)...
> >
> > In that case, let's assume it's not the same issue.
>
> Yeah, I think it amounts to the same thing, if EOF never arrives.
>
> I suspect that we could get ->safe_psql() down to about ~25ms baseline
> if someone could fix the posited IPC::Run EOF bug
I pushed optimizations in https://github.com/cpan-authors/IPC-Run/pull/172
that make the TAP portion of "make check-world" 7% faster on my GNU/Linux
machine. I didn't confirm an EOF bug, but that change also reduces Windows
idle time in simple tests. I didn't run Windows check-world with it. For
non-Windows, we can get almost all the benefit from the attached one-liner.
(The relative benefit is probably lower for parallel check-world, where idle
threads matter less, and for slower machines.)
Author: Noah Misch <n...@leadboat.com>
Commit: Noah Misch <n...@leadboat.com>
Backport IPC::Run optimization to src/test/perl.
This one-liner makes the TAP portion of "make check-world" 7% faster on
a non-Windows machine.
Reviewed by FIXME.
Discussion: https://postgr.es/m/FIXME
diff --git a/src/test/perl/PostgreSQL/Test/Utils.pm
b/src/test/perl/PostgreSQL/Test/Utils.pm
index 42d5a50..6f7a48b 100644
--- a/src/test/perl/PostgreSQL/Test/Utils.pm
+++ b/src/test/perl/PostgreSQL/Test/Utils.pm
@@ -189,6 +189,10 @@ Set to true when running under MSYS2.
INIT
{
+ # See https://github.com/cpan-authors/IPC-Run/commit/fc9288c for how
this
+ # reduces idle time. Remove this when IPC::Run 20231003.0 is too old to
+ # matter (when all versions that matter provide the optimization).
+ $SIG{CHLD} = sub { };
# Return EPIPE instead of killing the process with SIGPIPE. An affected
# test may still fail, but it's more likely to report useful facts.
