Re: Deadlock in multiple CIC.

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
Cc: Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Deadlock in multiple CIC.
Date: 2018-04-18 15:38:16
Message-ID: 9251.1524065896@sss.pgh.pa.us
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I wrote:
>>> (A couple of the other isolation tests do fail reliably under this
>>> scenario; is it worth hardening them?)

>> Yes, I think it's worth making them pass somehow -- see commits
>> f18795e7b74c, a0eae1a2eeb6.

> Will look into that too. I'm not sure that adding extra expected
> outputs is sane, though --- might be best to just force the intended
> isolation level within those tests.

Hmm, so one of the ones that fails is lock-update-delete, which I see
*already has* an alternate output file for serializable mode ... but
it doesn't match what I get:

*** /home/postgres/pgsql/src/test/isolation/expected/lock-update-delete_1.out Mon Feb 12 14:53:46 2018
--- /home/postgres/pgsql/src/test/isolation/output_iso/results/lock-update-delete.out Wed Apr 18 11:30:23 2018
***************
*** 150,156 ****

t
step s1l: <... completed>
! error in steps s2_unlock s1l: ERROR: could not serialize access due to concurrent update

starting permutation: s2b s1l s2u s2_blocker1 s2r s2_unlock
pg_advisory_lock
--- 150,158 ----

t
step s1l: <... completed>
! key value
!
! 1 1

starting permutation: s2b s1l s2u s2_blocker1 s2r s2_unlock
pg_advisory_lock

It looks like maybe this one wasn't updated in 533e9c6b0 --- would
you check/confirm that?

regards, tom lane

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