Re: HS locking broken in HEAD

On 2013-01-18 11:16:15 -0500, Tom Lane wrote:
> Andres Freund <andres@2ndquadrant.com> writes:
> > I am still stupefied nobody noticed that locking in HS (where just about
> > all locks are going to be fast path locks) was completely broken for
> > nearly two years.
> 
> IIUC it would only be broken for cases where activity was going on
> concurrently in two different databases, which maybe isn't all that
> common out in the field.  And for sure it isn't something we test much.

I think effectively it only was broken in Hot Standby. At least I don't
immediately can think of a scenario where a strong lock is being acquired on a
non-shared object in a different database.

> I wonder if it'd be practical to, say, run all the contrib regression
> tests concurrently in different databases of one installation.

I think it would be a good idea, but I don't immediately have an idea
how to implement it. It seems to me we would need to put the logic for
it into pg_regress? Otherwise the lifetime management of the shared
postmaster seems to get complicated.

What I would really like is to have some basic replication test scenario
in the regression tests. That seems like a dramatically undertested, but
pretty damn essential, part of the code.

The first handwavy guess I have of doing it is something like connecting
a second postmaster to the primary one at the start of the main
regression tests (requires changing the wal level again, yuck) and
fuzzyly comparing a pg_dump of the database remnants in both clusters at
the end of the regression tests.

Better ideas?

Greetings,

Andres Freund

-- Andres Freund                       http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
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