ghci and ghc -threaded broken with pipes & forking

Simon Marlow marlowsd at gmail.com
Thu Dec 11 05:41:24 EST 2008


Brian B wrote:
> Hi Bulat,
> 
> My contribution to the survey: I've used forkProcess to daemonize
> a ghc program inside the haskell fuse bindings:
> http://hackage.haskell.org/cgi-bin/hackage-scripts/package/HFuse
> http://code.haskell.org/hfuse/System/Fuse.hsc
> 
> If removing the non-threaded RTS would break forkProcess entirely,
> these bindings would have to do something different. The issue: users
> of the FUSE C api will get daemonized using daemon(2); it'd be
> nice if GHC fuse programs could behave similarly.

forkProcess should work with the threaded RTS, as long as you don't 
enable multiple cores with +RTS -N<n>.  However, forking is a pretty 
tricky operation in a multi-threaded environment, and that's where the 
difficulty comes from.

Cheers,
	Simon

> Thanks,
> Brian Bloniarz
> 
>  > Hello Tomasz,
>  >
>  > Saturday, December 6, 2008, 10:52:39 PM, you wrote:
>  >
>  > > Had you deprecated the non-threaded RTS, we would probably have no 
> problems
>  > > described in ticket #2848 :-/
>  >
>  > > I think you'll have to deprecate it anyway, because it will be more
>  > > and more difficult
>  > > to maintain two versions of code, especially if one of them will be
>  > > much less used and
>  > > tested.
>  >
>  > we may conduct small survey on amount of usage of old RTS (i mean ask
>  > this in haskell-cafe)
>  >
>  >
>  > --
>  > Best regards,
>  > Bulat mailto:Bulat.Ziganshin at gmail.com
>  >
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