Currently the priority of #4012 is normal, shouldn't it be at least high? Also the milestone is 7.12.1, should it be 7.10.2?
On Sun, May 10, 2015 at 3:39 PM, Mateusz Kowalczyk <fuuze...@fuuzetsu.co.uk> wrote: > Hi, > > I'd like to bring some attention to ticket #4012 about non-determinism. > As many of you may know, the nix package manager distributes binaries > throughout its binary caches. The binaries are shared as long as the > hash of some of their inputs matches: this means that we can end up with > two of the same hashes of inputs but thanks to #4012 means that the > actual contents can differ. You end up with machines with some packages > built locally and some elsewhere and due to non-determinism, the GHC > package IDs don't line up and everything is broken. > > The situation was pretty bad in 7.8.4 in presence of parallel builds so > we switched those off. Joachim's > a477e8118137b7483d0a7680c1fd337a007a023b helped a great deal there and > we were hopeful for 7.10. Now that 7.10.1 is out and people have been > using and testing it, the situation turns out to be really bad: daily we > get multiple reports from people about their packages ending up broken > and our only advice is to do what we did back in 7.8 days which is to > purge GHC and rebuild everything locally or fetch everything from a > machine that already built it all, as long as the two don't mix. This is > not really acceptable. > > See comment 76 on #4012 for an example of a rather simple file you can > compile right now with nothing extra but -O and get different interface > hash. > > This e-mail is just to raise awareness that there is a serious problem. > If people are thinking about cutting 7.10.2 or whatever, I would > consider part of this ticket to be a blocker as it makes using GHC > reliably while benefitting from binary caches pretty much impossible. > > Of course there's the ‘why don't you fix it yourself’ question. I > certainly plan to but do not have time for a couple more weeks to do so. > For all I know right now, the fix to comment 76 might be easy and > someone looking for something to hack on might have the time to get to > it before I do. > > Thanks > -- > Mateusz K. > _______________________________________________ > ghc-devs mailing list > ghc-devs@haskell.org > http://mail.haskell.org/cgi-bin/mailman/listinfo/ghc-devs >
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