[Haskell-cafe] Re: Parallel combinator, performance advice

[ChrisK]

You create one MVar for each task in order to ensure all the tasks are done.
This is pretty heavyweight.

You could create a single Control.Concurrent.QSemN to count the completed tasks,
starting with 0.

Each task is followed by signalQSemN with a value of 1.  (I would use "finally").

As parallel_ launches the tasks it can count their number, then it would call
waitQSemN for that quantity to have finished.

-- 
Chris