Re: [Haskell-cafe] multi-thread and lazy evaluation

I'm not sure that there is anything "great" about this bug.  It seems to me to be a rather severe demonstration of a somewhat already known design flaw in the runtime :( Could you please comment on the actual bug rather than replying here so that the devs see that this behaviour has been confirmed? Tim ---------- Původní zpráva ---------- Od: Corentin Dupont Datum: 25. 12. 2012 Předmět: Re: [Haskell-cafe] multi-thread and lazy evaluation " Great, with me compiled with ghc -threaded the bug shows up. However, runnning "main" in ghci doesn't show the bug (it finishes correctly). I have GHC 7.4.1.   Corentin On Tue, Dec 25, 2012 at 3:34 PM, wrote: " This seems like a bug in GHC. But it has nothing to do with MVars.  I've narrowed this down and filed a bug report here: http://hackage.haskell.org/trac/ghc/ticket/7528 (http://hackage.haskell.org/trac/ghc/ticket/7528) Timothy ---------- Původní zpráva ---------- Od: Yuras Shumovich Datum: 24. 12. 2012 Předmět: Re: [Haskell-cafe] multi-thread and lazy evaluation "On Mon, 2012-12-24 at 16:16 +0100, timothyhobbs@seznam.cz (mailto:timothyhobbs@seznam.cz) wrote:

The real question is, does this mean that GHC is stopping the world every time it puts an MVar?

No, GHC rts only locks the MVar itself. See here: http://hackage.haskell.org/trac/ghc/browser/rts/PrimOps.cmm#L1358 (http://hackage.haskell.org/trac/ghc/browser/rts/PrimOps.cmm#L1358) Yuras" _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org(mailto:Haskell-Cafe@haskell.org) http://www.haskell.org/mailman/listinfo/haskell-cafe (http://www.haskell.org/mailman/listinfo/haskell-cafe) " "