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

Hi, AFAIK it is (partially?) fixed in HEAD, see http://hackage.haskell.org/trac/ghc/ticket/367 It works for me with -fno-omit-yields Thanks, Yuras On Tue, 2012-12-25 at 19:35 +0100, timothyhobbs@seznam.cz wrote:

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)

"

"