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.
--- /dev/null
+-- !!! 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)