Thomas Munro wrote: > On 25 August 2014 02:57, Alvaro Herrera <alvhe...@2ndquadrant.com> wrote: > > Thomas Munro wrote: > >> The difficulty of course will be testing all these racy cases > >> reproducibly... > > > > Does this help? > > http://www.postgresql.org/message-id/51fb4305.3070...@2ndquadrant.com > > The useful trick there is forcing a query to get its snapshot and then > > go to sleep before actually doing anything, by way of an advisory lock. > > Yes it does, thanks Alvaro and Craig. I think the attached spec > reproduces the problem using that trick, ie shows NOWAIT blocking, > presumably in EvalPlanQualFetch (though I haven't stepped through it > with a debugger yet). I'm afraid I'm out of Postgres hacking cycles > for a few days, but next weekend I should have a new patch that fixes > this by teaching EvalPlanQualFetch about wait policies, with isolation > tests for NOWAIT and SKIP LOCKED.
Hmm, http://www.postgresql.org/message-id/51fb6703.9090...@2ndquadrant.com -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
