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PostgresNode::poll_query_until hacking

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: pgsql-hackers(at)postgreSQL(dot)org
Subject: PostgresNode::poll_query_until hacking
Date: 2017-07-01 19:53:02
Message-ID: 12486.1498938782@sss.pgh.pa.us (view raw, whole thread or download thread mbox)
Thread:
Lists: pgsql-hackers
The attached proposed patch changes the TAP test infrastructure's
poll_query_until function in two ways:

1. An optional argument is added to allow specifying the query result
value we're waiting for, overriding the normal "t".  This allows
folding a handwritten delay loop in 007_sync_rep.pl into the
poll_query_until ecosystem.  As far as I've found, there are no other
handwritten delay loops in the TAP tests.

2. poll_query_until is modified to probe 10X per second not once
per second, in keeping with the changes I've been making elsewhere
to remove not-carefully-analyzed 1s delays in the regression tests.

On my workstation, the reduced probe delay shaves a useful amount
of time off the recovery and subscription regression tests.  I also
tried it on dromedary, which is about the slowest hardware I'd care
to run the TAP tests on regularly, and it seems to be about a wash
there --- some tests get faster, but some get slower, presumably due
to more overhead from the probe queries.

I notice that buildfarm member skink (which runs with valgrind)
recently failed a test run due to poll_query_until timing out:

https://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=skink&dt=2017-06-30%2000%3A50%3A01

I'm inclined to respond to that either by increasing the fixed
180-second timeout, or by making it configurable from an environment
variable (which Andres would then have to add to skink's configuration).

Thoughts?

			regards, tom lane


Attachment: improve-poll_query_until.patch
Description: text/x-diff (3.6 KB)

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