[project @ 2000-08-25 13:26:57 by simonmar]

Add a test (also benchmark) for threadDelay, Random, and QSemN.  This
test starts a large number of threads which all wait for a random
delay.  The semaphore is used to wait for them all to finish before exiting.

ghc/tests/concurrent/should_run/conc023.hs

+-- !!! test threadDelay, Random, and QSemN.
+
+-- start a large number (n) of threads each of which will wait for a
+-- random delay between 0 and m seconds.  We use a semaphore to wait
+-- for all the threads to finish.
+
+import Random
+import Concurrent
+import Exception
+
+n = 5000  -- no. of threads
+m = 3000  -- maximum delay
+
+main = do
+   s <- newQSemN n
+   (is :: [Int]) <- sequence (take n (repeat (getStdRandom (randomR (1,m)))))
+   mapM (fork_sleep s) is
+   waitQSemN s n
+   where
+	fork_sleep s i = forkIO (do waitQSemN s 1
+			  	    threadDelay (i*1000)
+				    signalQSemN s 1)