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/* |
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* Written by Doug Lea with assistance from members of JCP JSR-166 |
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* Expert Group and released to the public domain, as explained at |
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* http://creativecommons.org/publicdomain/zero/1.0/ |
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*/ |
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|
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import java.util.*; |
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import java.util.concurrent.*; |
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import java.util.concurrent.atomic.*; |
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import java.util.concurrent.locks.*; |
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|
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public class ConcurrentDequeLoops { |
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static final ExecutorService pool = Executors.newCachedThreadPool(); |
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static AtomicInteger totalItems; |
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static boolean print = false; |
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|
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public static void main(String[] args) throws Exception { |
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int maxStages = 8; |
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int items = 1000000; |
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|
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Class<?> klass = null; |
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if (args.length > 0) { |
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try { |
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klass = Class.forName(args[0]); |
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} catch (ClassNotFoundException e) { |
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throw new RuntimeException("Class " + args[0] + " not found."); |
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} |
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} |
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else |
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throw new Error(); |
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|
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if (args.length > 1) |
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maxStages = Integer.parseInt(args[1]); |
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|
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System.out.print("Class: " + klass.getName()); |
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System.out.println(" stages: " + maxStages); |
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|
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print = false; |
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System.out.println("Warmup..."); |
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oneRun(klass, 1, items); |
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Thread.sleep(100); |
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oneRun(klass, 1, items); |
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Thread.sleep(100); |
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print = true; |
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|
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for (int k = 1, i = 1; i <= maxStages;) { |
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oneRun(klass, i, items); |
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if (i == k) { |
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k = i << 1; |
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i = i + (i >>> 1); |
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} |
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else |
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i = k; |
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} |
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pool.shutdown(); |
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} |
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|
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static class Stage implements Callable<Integer> { |
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final Deque<Integer> queue; |
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final CyclicBarrier barrier; |
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final LoopHelpers.SimpleRandom rng = new LoopHelpers.SimpleRandom(); |
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int items; |
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Stage(Deque<Integer> q, CyclicBarrier b, int items) { |
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queue = q; |
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barrier = b; |
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this.items = items; |
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} |
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|
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public Integer call() { |
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// Repeatedly take something from queue if possible, |
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// transform it, and put back in. |
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try { |
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barrier.await(); |
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int l = (int) System.nanoTime(); |
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int takes = 0; |
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for (;;) { |
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Integer item; |
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int rnd = rng.next(); |
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if ((rnd & 1) == 0) |
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item = queue.pollFirst(); |
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else |
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item = queue.pollLast(); |
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if (item != null) { |
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++takes; |
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l += LoopHelpers.compute2(item.intValue()); |
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} |
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else if (takes != 0) { |
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totalItems.getAndAdd(-takes); |
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takes = 0; |
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} |
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else if (totalItems.get() <= 0) |
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break; |
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l = LoopHelpers.compute1(l); |
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if (items > 0) { |
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--items; |
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Integer res = new Integer(l); |
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if ((rnd & 16) == 0) |
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queue.addFirst(res); |
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else |
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queue.addLast(res); |
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} |
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else { // spinwait |
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for (int k = 1 + (l & 15); k != 0; --k) |
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l = LoopHelpers.compute1(LoopHelpers.compute2(l)); |
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if ((l & 3) == 3) { |
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Thread.sleep(1); |
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} |
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} |
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} |
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return new Integer(l); |
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} |
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catch (Exception ie) { |
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ie.printStackTrace(); |
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throw new Error("Call loop failed"); |
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} |
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} |
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} |
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|
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static void oneRun(Class<?> klass, int n, int items) throws Exception { |
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Deque<Integer> q = |
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(Deque<Integer>) klass.getConstructor().newInstance(); |
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LoopHelpers.BarrierTimer timer = new LoopHelpers.BarrierTimer(); |
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CyclicBarrier barrier = new CyclicBarrier(n + 1, timer); |
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totalItems = new AtomicInteger(n * items); |
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ArrayList<Future<Integer>> results = new ArrayList<Future<Integer>>(n); |
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for (int i = 0; i < n; ++i) |
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results.add(pool.submit(new Stage(q, barrier, items))); |
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|
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if (print) |
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System.out.print("Threads: " + n + "\t:"); |
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barrier.await(); |
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int total = 0; |
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for (int i = 0; i < n; ++i) { |
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Future<Integer> f = results.get(i); |
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Integer r = f.get(); |
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total += r.intValue(); |
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} |
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long endTime = System.nanoTime(); |
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long time = endTime - timer.startTime; |
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if (print) |
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System.out.println(LoopHelpers.rightJustify(time / (items * n)) + " ns per item"); |
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if (total == 0) // avoid overoptimization |
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System.out.println("useless result: " + total); |
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} |
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} |
