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dl |
1.1 |
/* |
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* @test %I% %E% |
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* @bug 4486658 |
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* @compile -source 1.5 ConcurrentQueueLoops.java |
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* @run main/timeout=230 ConcurrentQueueLoops |
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* @summary Checks that a set of threads can repeatedly get and modify items |
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*/ |
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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. Use, modify, and |
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* redistribute this code in any way without acknowledgement. |
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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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public class ConcurrentQueueLoops { |
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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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public static void main(String[] args) throws Exception { |
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int maxStages = 8; |
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int items = 100000; |
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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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klass = java.util.concurrent.ConcurrentLinkedQueue.class; |
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if (args.length > 1) |
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maxStages = Integer.parseInt(args[1]); |
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System.out.print("Class: " + klass.getName()); |
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System.out.println(" stages: " + maxStages); |
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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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for (int i = 1; i <= maxStages; i += (i+1) >>> 1) { |
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oneRun(klass, i, items); |
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} |
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pool.shutdown(); |
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} |
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static class Stage implements Callable<Integer> { |
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final Queue<Integer> queue; |
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final CyclicBarrier barrier; |
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int items; |
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Stage (Queue<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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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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int seq = l; |
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for (;;) { |
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Integer item = queue.poll(); |
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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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while (!queue.offer(new Integer(l^seq++))) ; |
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} |
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else if ( (l & (3 << 5)) == 0) // spinwait |
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Thread.sleep(1); |
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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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static void oneRun(Class klass, int n, int items) throws Exception { |
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Queue<Integer> q = (Queue<Integer>)klass.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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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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} |