Re: pgbench logging broken by time logic changes

On Wed, Jun 16, 2021 at 03:13:30PM -0400, Andrew Dunstan wrote:
> On 6/16/21 2:59 PM, Fabien COELHO wrote:
> > The key feedback for me is the usual one: what is not tested does not
> > work. Wow:-)
> 
> Agreed.
> 
> > I'm unhappy because I already added tap tests for time-sensitive
> > features (-T and others, maybe logging aggregates, cannot remember),
> > which have been removed because they could fail under some
> > circonstances (eg very very very very slow hosts), or required some
> > special handling (a few lines of code) in pgbench, and the net result
> > of this is there is not a single test in place for some features:-(
> 
> I'm not familiar with exactly what happened in this case, but tests need
> to be resilient over a wide range of performance characteristics. One
> way around this issue might be to have a way of detecting that it's on a
> slow platform and if so either skipping tests (Test::More provides
> plenty of support for this) or expecting different results.

Detection would need the host to be consistently slow, like running under
Valgrind or a 20-year-old CPU.  We also test on systems having highly-variable
performance due to other processes competing for the same hardware.  I'd
perhaps add a "./configure --enable-realtime-tests" option that enables
affected tests.  Testers should use the option whenever the execution
environment has sufficient reserved CPU.