Re: isolation test deadlocking on buildfarm member coypu

After committing Noah's patch to fix the isolation tests, there have
been two more failures in Rémi's machines pika and coypu:

http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=pika&dt=2011-07-24%2006%3A45%3A45
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=coypu&dt=2011-07-23%2021%3A50%3A54

In both cases, the failure is identical in fk-deadlock2:

================== pgsql.20950/src/test/isolation/regression.diffs ===================
*** /home/pgbuildfarm/workdir/HEAD/pgsql.20950/src/test/isolation/expected/fk-deadlock2.out Sun Jul 24 08:46:44 2011
--- /home/pgbuildfarm/workdir/HEAD/pgsql.20950/src/test/isolation/results/fk-deadlock2.out Sun Jul 24 15:11:42 2011
***************
*** 22,29 ****
step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
- step s1u2: <... completed>
ERROR: deadlock detected
step s1c: COMMIT;
step s2c: COMMIT;

--- 22,29 ----
step s2u1: UPDATE B SET Col2 = 1 WHERE BID = 2;
step s1u2: UPDATE B SET Col2 = 1 WHERE BID = 2; <waiting ...>
step s2u2: UPDATE B SET Col2 = 1 WHERE BID = 2;
ERROR: deadlock detected
+ step s1u2: <... completed>
step s1c: COMMIT;
step s2c: COMMIT;

I think the only explanation necessary for this is that one process
reports its status before the other one. I think it would be enough to
add another variant of the expected file to fix this problem, but I
don't quite want to do that because we already have three of them, and I
think we would need to add one per existing expected, so we'd end up
with 6 expected files which would be a pain to work with.

Not quite sure what to do with this.

--
Álvaro Herrera <alvherre(at)commandprompt(dot)com>
The PostgreSQL Company - Command Prompt, Inc.
PostgreSQL Replication, Consulting, Custom Development, 24x7 support