test/loops/DynamicFib.java

import java.util.concurrent.*;

public final class DynamicFib extends RecursiveAction {
    static int procs;
    static long lastStealCount; // to display steal counts

    /** for time conversion */
    static final long NPS = (1000L * 1000 * 1000);

    public static void main(String[] args) throws Exception {
        procs = 0;
        int num = 45;
        try {
            if (args.length > 0)
                procs = Integer.parseInt(args[0]);
            if (args.length > 1)
                num = Integer.parseInt(args[1]);
        }
        catch (Exception e) {
            System.out.println("Usage: java DynamicFib <threads> <number>");
            return;
        }
        for (int reps = 0; reps < 2; ++reps) {
            ForkJoinPool pool = (procs == 0) ? new ForkJoinPool() :
                new ForkJoinPool(procs);
            for (int i = 0; i < 20; ++i)
                test(pool, num);
            System.out.println(pool);
            pool.shutdown();
        }
    }

    static void test(ForkJoinPool pool, int num) throws Exception {
        int ps = pool.getParallelism();
        long start = System.nanoTime();
        DynamicFib f = new DynamicFib(num);
        pool.invoke(f);
        long time = System.nanoTime() - start;
        double secs = ((double)time) / NPS;
        long result = f.number;
        System.out.print("DynamicFib " + num + " = " + result);
        System.out.printf("\tTime: %9.3f", secs);
        long sc = pool.getStealCount();
        long ns = sc - lastStealCount;
        lastStealCount = sc;
        System.out.printf(" Steals: %4d", ns/ps);
        System.out.printf(" Workers: %4d", pool.getPoolSize());
        System.out.println();
    }


    int number;     // Initialized with argument; replaced with result
    DynamicFib(int n) { number = n; }
    public void compute() {
        number = fib(number);
    }

    static int fib(int n) {
        int res;
        if (n <= 1)
            res = n;
        else if (getSurplusQueuedTaskCount() >= 4)
            res = seqFib(n);
        else {
            DynamicFib f2 = new DynamicFib(n - 2);
            f2.fork();
            res = fib(n - 1);
            if (f2.tryUnfork())
                res += fib(n - 2);
            else {
                f2.quietlyJoin();
                res += f2.number;
            }
        }
        return res;
    }

    // Sequential version for arguments less than threshold
    static final int seqFib(int n) { // unroll left only
        int r = 1;
        do {
            int m = n - 2;
            r += m <= 1 ? m : seqFib(m);
        } while (--n > 1);
        return r;
    }

}

Revision:	1.3
Committed:	Mon Nov 29 20:58:06 2010 UTC (13 years, 5 months ago) by jsr166
Branch:	MAIN
CVS Tags:	release-1_7_0
Changes since 1.2:	+1 -1 lines
Log Message:	consistent ternary operator style
#	User	Rev	Content
1	dl	1.1	import java.util.concurrent.*;
2
3			public final class DynamicFib extends RecursiveAction {
4			static int procs;
5			static long lastStealCount; // to display steal counts
6
7			/** for time conversion */
8			static final long NPS = (1000L * 1000 * 1000);
9
10			public static void main(String[] args) throws Exception {
11			procs = 0;
12			int num = 45;
13			try {
14			if (args.length > 0)
15			procs = Integer.parseInt(args[0]);
16			if (args.length > 1)
17			num = Integer.parseInt(args[1]);
18			}
19			catch (Exception e) {
20			System.out.println("Usage: java DynamicFib <threads> <number>");
21			return;
22			}
23			for (int reps = 0; reps < 2; ++reps) {
24	jsr166	1.3	ForkJoinPool pool = (procs == 0) ? new ForkJoinPool() :
25	dl	1.1	new ForkJoinPool(procs);
26	jsr166	1.2	for (int i = 0; i < 20; ++i)
27	dl	1.1	test(pool, num);
28			System.out.println(pool);
29			pool.shutdown();
30			}
31			}
32
33			static void test(ForkJoinPool pool, int num) throws Exception {
34			int ps = pool.getParallelism();
35			long start = System.nanoTime();
36			DynamicFib f = new DynamicFib(num);
37			pool.invoke(f);
38			long time = System.nanoTime() - start;
39			double secs = ((double)time) / NPS;
40			long result = f.number;
41			System.out.print("DynamicFib " + num + " = " + result);
42			System.out.printf("\tTime: %9.3f", secs);
43			long sc = pool.getStealCount();
44			long ns = sc - lastStealCount;
45			lastStealCount = sc;
46			System.out.printf(" Steals: %4d", ns/ps);
47			System.out.printf(" Workers: %4d", pool.getPoolSize());
48			System.out.println();
49			}
50
51
52			int number; // Initialized with argument; replaced with result
53			DynamicFib(int n) { number = n; }
54	jsr166	1.2	public void compute() {
55			number = fib(number);
56	dl	1.1	}
57
58			static int fib(int n) {
59			int res;
60	jsr166	1.2	if (n <= 1)
61	dl	1.1	res = n;
62			else if (getSurplusQueuedTaskCount() >= 4)
63			res = seqFib(n);
64			else {
65			DynamicFib f2 = new DynamicFib(n - 2);
66			f2.fork();
67			res = fib(n - 1);
68			if (f2.tryUnfork())
69			res += fib(n - 2);
70			else {
71			f2.quietlyJoin();
72			res += f2.number;
73			}
74			}
75			return res;
76			}
77
78			// Sequential version for arguments less than threshold
79			static final int seqFib(int n) { // unroll left only
80			int r = 1;
81			do {
82			int m = n - 2;
83			r += m <= 1 ? m : seqFib(m);
84			} while (--n > 1);
85			return r;
86			}
87
88			}
89