[Haskell-cafe] True parallelism missing :-(

[Roberto Zunino]

Dusan Kolar wrote:
> Dear all,
> 
>  I've thought the following three (dummy) programs would run some of 
> their parts in parallel (on dual core) if compiled with option threaded 
> (smp). The truth is that only the first one exploits multicore CPU. Why?

>          h1 <- forkIO $ putMVar v1 $ fibs (n-1)

You are putting an unevaluated thunk in the MVar. Try:

h1 <- forkIO (putMVar v1 $! fibs (n-1))

Zun.