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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 jsr166y.*; |
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|
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/** |
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* Based loosely on Java Grande Forum barrierBench |
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*/ |
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public class SpinningTieredPhaserLoops { |
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static final int NCPUS = Runtime.getRuntime().availableProcessors(); |
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static final ExecutorService pool = Executors.newCachedThreadPool(); |
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static final int FIRST_SIZE = 10000; |
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static final int LAST_SIZE = 1000000; |
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/** for time conversion */ |
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static final long NPS = (1000L * 1000 * 1000); |
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|
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static int tasksPerPhaser = Math.max(NCPUS / 4, 4); |
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|
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static void build(Runnable[] actions, int sz, int lo, int hi, Phaser b) { |
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if (hi - lo > tasksPerPhaser) { |
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for (int i = lo; i < hi; i += tasksPerPhaser) { |
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int j = Math.min(i + tasksPerPhaser, hi); |
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build(actions, sz, i, j, new Phaser(b)); |
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} |
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} else { |
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for (int i = lo; i < hi; ++i) |
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actions[i] = new PhaserAction(i, b, sz); |
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} |
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} |
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|
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static final class PhaserAction implements Runnable { |
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final int id; |
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final int size; |
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final Phaser phaser; |
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public PhaserAction(int id, Phaser b, int size) { |
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this.id = id; |
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this.phaser = b; |
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this.size = size; |
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phaser.register(); |
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} |
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|
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|
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public void run() { |
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int n = size; |
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Phaser b = phaser; |
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for (int i = 0; i < n; ++i) { |
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int p = b.arrive(); |
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while (b.getPhase() == p) { |
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if ((ThreadLocalRandom.current().nextInt() & 127) == 0) |
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Thread.yield(); |
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} |
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} |
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} |
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} |
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|
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public static void main(String[] args) throws Exception { |
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int nthreads = NCPUS; |
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if (args.length > 0) |
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nthreads = Integer.parseInt(args[0]); |
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if (args.length > 1) |
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tasksPerPhaser = Integer.parseInt(args[1]); |
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|
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System.out.printf("Max %d Threads, %d tasks per phaser\n", nthreads, tasksPerPhaser); |
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|
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for (int k = 2; k <= nthreads; k *= 2) { |
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for (int size = FIRST_SIZE; size <= LAST_SIZE; size *= 10) { |
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long startTime = System.nanoTime(); |
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|
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Runnable[] actions = new Runnable [k]; |
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build(actions, size, 0, k, new Phaser()); |
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Future[] futures = new Future[k]; |
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for (int i = 0; i < k; ++i) { |
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futures[i] = pool.submit(actions[i]); |
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} |
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for (int i = 0; i < k; ++i) { |
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futures[i].get(); |
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} |
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long elapsed = System.nanoTime() - startTime; |
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long bs = (NPS * size) / elapsed; |
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System.out.printf("%4d Threads %8d iters: %11d barriers/sec\n", |
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k, size, bs); |
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} |
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} |
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pool.shutdown(); |
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} |
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|
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} |
