Feedback-ID: id4a34324:Fastmail
Date: Tue, 12 Sep 2023 16:49:01 -0700
From: Andres Freund <andres@anarazel.de>
To: Daniel Gustafsson <daniel@yesql.se>
Cc: Tom Lane <tgl@sss.pgh.pa.us>,
	PostgreSQL Hackers <pgsql-hackers@postgresql.org>,
	Thomas Munro <thomas.munro@gmail.com>,
	Justin Pryzby <pryzby@telsasoft.com>,
	Nazir Bilal Yavuz <byavuz81@gmail.com>
Subject: Re: Cirrus-ci is lowering free CI cycles - what to do with cfbot,
 etc?
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Hi,

On 2023-08-30 10:57:10 +0200, Daniel Gustafsson wrote:
> > On 28 Aug 2023, at 14:32, Daniel Gustafsson <daniel@yesql.se> wrote:
> 
> > Attached is a patch with a quick PoC for using PQPing instead of using psql for
> > connection checks in pg_regress.
> 
> The attached v2 fixes a silly mistake which led to a compiler warning.

Still seems like a good idea to me. To see what impact it has, I measured the
time running the pg_regress tests that take less than 6s on my machine - I
excluded the slower ones (like the main regression tests) because they'd hide
any overall difference.

ninja && m test --suite setup --no-rebuild && tests=$(m test --no-rebuild --list|grep -E '/regress'|grep -vE '(regress|postgres_fdw|test_integerset|intarray|amcheck|test_decoding)/regress'|cut -d' ' -f 3) && time m test --no-rebuild $tests

Time for:


master:

cassert:
real	0m5.265s
user	0m8.422s
sys	0m8.381s

optimized:
real	0m4.926s
user	0m6.356s
sys	0m8.263s


my patch (probing every 100ms with psql):

cassert:
real	0m3.465s
user	0m8.827s
sys	0m8.579s

optimized:
real	0m2.932s
user	0m6.596s
sys	0m8.458s


Daniel's (probing every 50ms with PQping()):

cassert:
real	0m3.347s
user	0m8.373s
sys	0m8.354s

optimized:
real	0m2.527s
user	0m6.156s
sys	0m8.315s


My patch increased user/sys time a bit (likely due to a higher number of
futile psql forks), but Daniel's doesn't. And it does show a nice overall wall
clock time saving.

Greetings,

Andres Freund