[Haskell-cafe] Debugging a test suite freeze

Doug Burke dburke.gw at gmail.com
Thu Dec 1 13:38:10 UTC 2022


Sorry, mea culpa. I got confused - there was a test loop with 9.2
(which sounded a bit like your case, but it was in 9.2 and not 9.4)
and an unrelated issue with 9.4 that was found at the same time and I
got that mixed up

Doug

On Wed, Nov 30, 2022 at 11:15 PM David Feuer <david.feuer at gmail.com> wrote:
>
> I don't see anything about test suites freezing/looping in that
> ticket. Did you mean a different one? Note: it seems pretty clear that
> my test suite is *not* looping: when it freezes, the process doesn't
> burn CPU or memory. It seems there's a deadlock somewhere, but it's
> all *extremely* mysterious to me. Most mysteriously, only the last
> test case seems to lead to this problem, and it does so even when
> *dramatically* simplified in various ways (e.g., if I just `liftIO
> (print s)` instead of traversing with an arbitrary function, and then
> finish off with `3 === 3`). It would be easy to believe that the
> problem was in my Hedgehog test case generation code if not for the
> fact that it works reliably on all versions of GHC from 7.8 through
> 9.2! So either something is wrong with GHC 9.4 or using 9.4 is getting
> me a bad version of some dependency.
>
> On Wed, Nov 30, 2022 at 10:36 PM Doug Burke <dburke.gw at gmail.com> wrote:
> >
> > I had a test suite loop indefinitely with ghc 9.4.3 - see
> > https://gitlab.haskell.org/ghc/ghc/-/issues/22416 - but to be honest I
> > don't really understand what the code did that lead to the problem, so
> > dont know how relevant it is for you.
> >
> > Doug
> >
> > On Wed, Nov 30, 2022 at 5:46 PM David Feuer <david.feuer at gmail.com> wrote:
> > >
> > > In particular, I think tasty does some tricky concurrency. Have there been changes in that recently, either in GHC itself or in async, that might be responsible?
> > >
> > > On Wed, Nov 30, 2022, 5:33 PM David Feuer <david.feuer at gmail.com> wrote:
> > >>
> > >> The logict-sequence test suite consistently freezes up on the last
> > >> test when compiled with GHC 9.4.3. logict-sequence and its test suite
> > >> don't do anything special with that GHC/base version as far as I can
> > >> see, or anything particularly strange in general, so I'm pretty
> > >> confident the problem lies elsewhere. My best guesses are hedgehog,
> > >> tasty, and tasty-hedgehog. Has anyone else run into weird issues with
> > >> any/all of these on GHC 9.4.3?
> > >>
> > >> David
> > >
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