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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> |
16 |
< |
**/ |
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< |
|
16 |
> |
*/ |
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public final class Fib extends RecursiveAction { |
18 |
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|
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// Performance-tuning constant: |
20 |
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static int sequentialThreshold; |
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|
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static long lastStealCount; |
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< |
|
23 |
> |
|
24 |
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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; |
30 |
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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]); |
33 |
< |
if (args.length > 2) |
33 |
> |
if (args.length > 2) |
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sequentialThreshold = Integer.parseInt(args[2]); |
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} |
36 |
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catch (Exception e) { |
39 |
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} |
40 |
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|
41 |
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for (int reps = 0; reps < 2; ++reps) { |
42 |
< |
ForkJoinPool g = procs == 0? new ForkJoinPool() : |
42 |
> |
ForkJoinPool g = (procs == 0) ? new ForkJoinPool() : |
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new ForkJoinPool(procs); |
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lastStealCount = g.getStealCount(); |
45 |
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for (int i = 0; i < 20; ++i) { |
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long result = f.getAnswer(); |
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System.out.print("Fib " + num + " = " + result); |
73 |
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System.out.printf("\tTime: %7.3f", secs); |
74 |
< |
|
74 |
> |
|
75 |
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long sc = g.getStealCount(); |
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long ns = sc - lastStealCount; |
77 |
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lastStealCount = sc; |
98 |
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else { |
99 |
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Fib f1 = new Fib(n - 1); |
100 |
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Fib f2 = new Fib(n - 2); |
101 |
< |
// forkJoin(f1, f2); |
102 |
< |
invokeAll(f1, f2); |
101 |
> |
// forkJoin(f1, f2); |
102 |
> |
invokeAll(f1, f2); |
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number = f1.number + f2.number; |
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} |
105 |
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} |