From: Tom Lane <tgl@sss.pgh.pa.us>
To: Noah Misch <noah@leadboat.com>
cc: Andres Freund <andres@anarazel.de>, pgsql-hackers@postgresql.org
Subject: Re: Timeout control within tests
In-reply-to: <20220218071911.GB3506226@rfd.leadboat.com>
References: <20220218052842.GA3627003@rfd.leadboat.com> <20220218054825.vhoiv2f7vgwdsnnb@alap3.anarazel.de> <20220218071911.GB3506226@rfd.leadboat.com>
Comments: In-reply-to Noah Misch <noah@leadboat.com>
	message dated "Thu, 17 Feb 2022 23:19:11 -0800"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <3949562.1645198012.1@sss.pgh.pa.us>
Date: Fri, 18 Feb 2022 10:26:52 -0500
Message-ID: <3949563.1645198012@sss.pgh.pa.us>
Archived-At: <https://www.postgresql.org/message-id/3949563.1645198012%40sss.pgh.pa.us>
Precedence: bulk

Noah Misch <noah@leadboat.com> writes:
> On Thu, Feb 17, 2022 at 09:48:25PM -0800, Andres Freund wrote:
>> Meson's test runner has the concept of a "timeout multiplier" for ways of
>> running tests. Meson's stuff is about entire tests (i.e. one tap test), so
>> doesn't apply here, but I wonder if we shouldn't do something similar?

> Hmmm.  It is good if the user can express an intent that continues to make
> sense if we change the default timeout.  For the buildfarm use case, a
> multiplier is moderately better on that axis (PG_TEST_TIMEOUT_MULTIPLIER=100
> beats PG_TEST_TIMEOUT_DEFAULT=18000).  For the hacker use case, an absolute
> value is substantially better on that axis (PG_TEST_TIMEOUT_DEFAULT=3 beats
> PG_TEST_TIMEOUT_MULTIPLIER=.016666).

FWIW, I'm fairly sure that PGISOLATIONTIMEOUT=300 was selected after
finding that smaller values didn't work reliably in the buildfarm.
Now maybe 741d7f1 fixed that, but I wouldn't count on it.  So while I
approve of the idea to remove PGISOLATIONTIMEOUT in favor of using this
centralized setting, I think that we might need to have a multiplier
there, or else we'll end up with PG_TEST_TIMEOUT_DEFAULT set to 300
across the board.  Perhaps the latter is fine, but a multiplier seems a
bit more flexible.

On the other hand, I also support your point that an absolute setting
is easier to think about / adjust for special uses.  So maybe we should
just KISS and use a single absolute setting until we find a hard reason
why that doesn't work well.

			regards, tom lane