I have taken Larry's "Game of Life" example that he originally posted here:
http://groups.google.com/group/clojure/msg/fdfc88f1ba95bdee ...and updated it to use all the CPU's your JVM has access to. My first attempts ran into the classic map -> pmap slowdown. My next attempt had too much dosync, in that there were many threads but they were all waiting for each other. I finally rewrote the calc-state routine to batch the units of work into meaty sizes, and to minimize the dosync granularity. It gets the batches of new-state together, then goes and applies these in batches. In both events I use pmap. Now it is running really fast on my 4-core Intel i7. You will really notice a difference at larger grid sizes. On my i7 it keeps the 8 (due to hyperthreading) "cpus" busy at about 60% when I run a huge grid. I also updated paint-cells with a type hint that greatly reduces reflection in that performance critical code. I am very new to clojure and would appreciate feedback. I am concerned I may have overcomplicated things with my usage of the map/pmap form. I am guessing there may be a simpler way to write what I did. Note at the start it will automatically select how many "available- procs" you have. Try tweaking this on your hardware to see how it impacts performance. Watching the threads with a profiler is interesting. Here is is: (def cells (ref {})) (def running (ref false)) ;(def x-cells ( * 32 4)) ;(def y-cells ( * 48 4)) (def x-cells 32) (def y-cells 32) (def range-cells (for [x (range x-cells) y (range y-cells)] [x y])) (def length-range-cells (count range-cells)) (def cell-size 10) (def life-delay 0) (def life-initial-prob 3) (def available-procs (.. java.lang.Runtime getRuntime availableProcessors)) (defn determine-initial-state [x y] (= 0 (rand-int life-initial-prob))) (defn determine-new-state [x y] (let [alive (count (for [dx [-1 0 1] dy [-1 0 1] :when (and (not (= 0 dx dy)) (cells [ (mod (+ x dx) x-cells) (mod (+ y dy) y-cells)]))] :alive))] (if (cells [x y]) (< 1 alive 4) (= alive 3)))) (defn update-batch-of-new-cells [new-cells list-of-batches] (dosync (dorun (map #(commute new-cells assoc (first %) (second %)) list-of-batches)) )) (defn calc-batch-of-new-cell-states [cell-state batch-cells] (doall (map #(let [new-cell-state (cell-state (first %) (second %))] [[(first %) (second %)] new-cell-state]) batch-cells))) (defn calc-state [cell-state] (let [new-cells (ref {})] (dorun (pmap #(update-batch-of-new-cells new-cells %) (pmap #(calc-batch-of-new-cell-states cell-state %) (for [cpu (range available-procs)] (take-nth available- procs (drop cpu range-cells)))))) (dosync (ref-set cells @new-cells)))) (defn paint-cells [#^java.awt.Graphics graphics] (doseq [[[x,y] state] @cells] (doto graphics (. setColor (if state Color/RED Color/WHITE)) (. fillRect (* cell-size x) (* cell-size y) cell-size cell- size)))) (defn toggle-thread [#^JPanel panel button] (if @running (do (dosync (ref-set running false)) (. button (setText "Start"))) (do (dosync (ref-set running true)) (. button (setText "Stop")) (. (Thread. #(loop [] (calc-state determine-new-state) (. panel repaint) (if life-delay (Thread/sleep life-delay)) (if @running (recur)))) start)))) (defn -main[] (calc-state determine-initial-state) (let [f (JFrame.) b (JButton. "Start") panel (proxy [JPanel] [] (paint [graphics] (paint-cells graphics)))] (doto f (. setLayout (BorderLayout.)) (. setLocation 100 100) (. setPreferredSize (Dimension. (* cell-size x-cells) (+ 60 (* cell-size y-cells)))) (. add b BorderLayout/SOUTH) (. add panel BorderLayout/CENTER) (. setDefaultCloseOperation JFrame/EXIT_ON_CLOSE) (. pack) (. setVisible true)) (. b addActionListener (proxy [ActionListener] [] (actionPerformed [evt] (toggle-thread panel b)))))) --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
