[Haskell-cafe] Re: Automatic parallelism in Haskell, similar to "make -j4"?

Bulat Ziganshin wrote:

Hello Chad,

Wednesday, November 5, 2008, 6:34:01 AM, you wrote:

...

ghc --make -j4 Foo.hs

afair, it was implemented and not shown speed improvements. ask Simon

We did get speed improvements, it was the main case study for the initial implementation of shared-memory parallelism in GHC. See http://www.haskell.org/~simonmar/bib/multiproc05_abstract.html However, due to the way GHC is structured internally (it has some global caches updated using unsafePerformIO!) the parallel make implementation was quite fragile, and wasn't suitable for incorporating into GHC proper. It's certainly possible, but we need to think carefully about how to make these caches multi-thread-safe. Cheers, Simon