ThreadScope Tour/Run

Objective

Run ThreadScope on a sample program and get a trace.

Steps

1. Copy the following parallel code to hellofib.hs

    import Control.Parallel.Strategies
    import System.Environment
   
    fib 0 = 1
    fib 1 = 1
    fib n = runEval $ do
      x <- rpar (fib (n-1))
      y <- rseq (fib (n-2))
      return (x + y + 1)
   
    main = do
      args <- getArgs
      n <- case args of
            []    -> return 20 
            [x]   -> return (read x)
            _     -> fail ("Usage: hellofib [n]")
      print (fib n)

2. Build hellofib.hs

    ghc -O2 -rtsopts -eventlog -threaded hellofib

3. Run hellofib

    ./hellofib +RTS -N2

4. View its trace

   threadscope hellofib.eventlog # on Windows, may be hellofib.exe.eventlog