Parallel processing in Clojure

pmap.clj

(defn sleep []
  (Thread/sleep 1000))

(defn fast-computation [x]
  (* x 2))

(defn heavy-computation [x]
  (sleep)
  (* x 2))

; pmap helps you make heavy computations faster

(time (doall (map heavy-computation [1 2 3 4 5])))
; "Elapsed time: 5002.32348 msecs"
; (2 4 6 8 10)

(time (doall (pmap heavy-computation [1 2 3 4 5])))
; "Elapsed time: 1003.531455 msecs"
; (2 4 6 8 10)

; but your fast computations can become slower

(time (doall (map fast-computation [1 2 3 4 5])))
; "Elapsed time: 0.156445 msecs"
; (2 4 6 8 10)

(time (doall (pmap fast-computation [1 2 3 4 5])))
; "Elapsed time: 0.938946 msecs"
; (2 4 6 8 10)