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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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import java.util.concurrent.*; |
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/** |
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* Recursive task-based version of Fibonacci. Computes: |
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* <pre> |
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* Computes fibonacci(n) = fibonacci(n-1) + fibonacci(n-2); for n> 1 |
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* fibonacci(0) = 0; |
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* fibonacci(1) = 1. |
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* fibonacci(0) = 0; |
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* fibonacci(1) = 1. |
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* </pre> |
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**/ |
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*/ |
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public final class FibTask extends RecursiveTask<Integer> { |
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// Performance-tuning constant: |
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static int sequentialThreshold; |
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static long lastStealCount; |
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public static void main(String[] args) throws Exception { |
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int procs = 0; |
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int num = 45; |
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procs = Integer.parseInt(args[0]); |
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if (args.length > 1) |
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num = Integer.parseInt(args[1]); |
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if (args.length > 2) |
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if (args.length > 2) |
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sequentialThreshold = Integer.parseInt(args[2]); |
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} |
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catch (Exception e) { |
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} |
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for (int reps = 0; reps < 2; ++reps) { |
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ForkJoinPool g = procs == 0? new ForkJoinPool() : |
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ForkJoinPool g = (procs == 0) ? new ForkJoinPool() : |
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new ForkJoinPool(procs); |
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lastStealCount = g.getStealCount(); |
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for (int i = 0; i < 20; ++i) { |
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double secs = ((double)time) / NPS; |
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System.out.print("FibTask " + num + " = " + result); |
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System.out.printf("\tTime: %7.3f", secs); |
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long sc = g.getStealCount(); |
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long ns = sc - lastStealCount; |
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lastStealCount = sc; |
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FibTask f1 = new FibTask(n - 1); |
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f1.fork(); |
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FibTask f2 = new FibTask(n - 2); |
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return f2.compute() + f1.join(); |
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return f2.compute() + f1.join(); |
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} |
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} |
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return r; |
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} |
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} |
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– |
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