Re: Deadlock in multiple CIC.

From: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>
To: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
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 15:36:26
Message-ID: 20180418153626.didla63talgczupk@alvherre.pgsql
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Tom Lane wrote:

> Anyway, at this point I'm going to give up on the debug logging, revert
> 9.4 to its prior state, and then see if the transaction-restart patch
> makes the problem go away.

Agreed, thanks.

> >> (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.

As I recall (not much, admittedly) that was one of the options we
considered in the old commit, but since the other isolation levels
behaved differently we ageed that it was worth adding coverage for them.
I don't know which ones are failing now; maybe forcing a specific
isolation level is sufficient.

Clearly we should have done something to make sure these tests were run
periodically with different isolation levels.

--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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