test/loops/DynamicLeftSpineFib.java

//import jsr166y.*;
import java.util.*;
import java.util.concurrent.*;

public final class DynamicLeftSpineFib extends RecursiveAction {

    // Performance-tuning constant:
    static long lastStealCount;

    public static void main(String[] args) throws Exception {
        int procs = 0;
        int num = 43;
        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 DynamicLeftSpineFib <threads> <number> [<sequntialThreshold>]");
            return;
        }


        for (int reps = 0; reps < 2; ++reps) {
            ForkJoinPool g = procs == 0? new ForkJoinPool() :
                new ForkJoinPool(procs);
            lastStealCount = g.getStealCount();
            for (int i = 0; i < 10; ++i) {
                test(g, num);
            }
            System.out.println(g);
            g.shutdown();
        }
    }

    static void test(ForkJoinPool g, int num) throws Exception {
        int ps = g.getParallelism();
        long start = System.currentTimeMillis();
        DynamicLeftSpineFib f = new DynamicLeftSpineFib(num, null);
        g.invoke(f);
        long time = System.currentTimeMillis() - start;
        double secs = ((double)time) / 1000.0;
        long result = f.getAnswer();
        System.out.print("DynamicLeftSpineFib " + num + " = " + result);
        System.out.printf("\tTime: %7.3f", secs);
        long sc = g.getStealCount();
        long ns = sc - lastStealCount;
        lastStealCount = sc;
        System.out.printf(" Steals/t: %5d", ns/ps);
        System.out.printf(" Workers: %8d", g.getPoolSize());
        System.out.println();
    }


    // Initialized with argument; replaced with result
    int number;
    DynamicLeftSpineFib next;

    DynamicLeftSpineFib(int n, DynamicLeftSpineFib nxt) {
        number = n; next = nxt;
    }

    int getAnswer() {
        return number;
    }

    public final void compute() {
        int n = number;
        if (n > 1) {
            DynamicLeftSpineFib rt = null;
            while (n > 1 && getSurplusQueuedTaskCount() <= 3) {
                (rt = new DynamicLeftSpineFib(n - 2, rt)).fork();
                n -= 1;
            }
            int r = seqFib(n);
            while (rt != null) {
                if (rt.tryUnfork()) rt.compute(); else rt.helpJoin();
                r += rt.number;
                rt = rt.next;
            }
            number = r;
        }
    }

    // Sequential version for arguments less than threshold
    static int seqFib(int n) {
        if (n <= 1)
            return n;
        else
            return seqFib(n-1) + seqFib(n-2);
    }

}
Revision:	1.2
Committed:	Thu Oct 29 23:09:07 2009 UTC (14 years, 6 months ago) by jsr166
Branch:	MAIN
Changes since 1.1:	+7 -8 lines
Log Message:	whitespace
#	User	Rev	Content
1	dl	1.1	//import jsr166y.*;
2			import java.util.*;
3			import java.util.concurrent.*;
4
5			public final class DynamicLeftSpineFib extends RecursiveAction {
6
7			// Performance-tuning constant:
8			static long lastStealCount;
9	jsr166	1.2
10	dl	1.1	public static void main(String[] args) throws Exception {
11			int procs = 0;
12			int num = 43;
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 DynamicLeftSpineFib <threads> <number> [<sequntialThreshold>]");
21			return;
22			}
23
24	jsr166	1.2
25	dl	1.1	for (int reps = 0; reps < 2; ++reps) {
26			ForkJoinPool g = procs == 0? new ForkJoinPool() :
27			new ForkJoinPool(procs);
28			lastStealCount = g.getStealCount();
29			for (int i = 0; i < 10; ++i) {
30			test(g, num);
31			}
32			System.out.println(g);
33			g.shutdown();
34			}
35			}
36
37			static void test(ForkJoinPool g, int num) throws Exception {
38			int ps = g.getParallelism();
39			long start = System.currentTimeMillis();
40			DynamicLeftSpineFib f = new DynamicLeftSpineFib(num, null);
41			g.invoke(f);
42			long time = System.currentTimeMillis() - start;
43			double secs = ((double)time) / 1000.0;
44			long result = f.getAnswer();
45			System.out.print("DynamicLeftSpineFib " + num + " = " + result);
46			System.out.printf("\tTime: %7.3f", secs);
47			long sc = g.getStealCount();
48			long ns = sc - lastStealCount;
49			lastStealCount = sc;
50			System.out.printf(" Steals/t: %5d", ns/ps);
51			System.out.printf(" Workers: %8d", g.getPoolSize());
52			System.out.println();
53			}
54
55
56			// Initialized with argument; replaced with result
57			int number;
58			DynamicLeftSpineFib next;
59
60	jsr166	1.2	DynamicLeftSpineFib(int n, DynamicLeftSpineFib nxt) {
61			number = n; next = nxt;
62	dl	1.1	}
63
64			int getAnswer() {
65			return number;
66			}
67
68			public final void compute() {
69			int n = number;
70			if (n > 1) {
71			DynamicLeftSpineFib rt = null;
72			while (n > 1 && getSurplusQueuedTaskCount() <= 3) {
73			(rt = new DynamicLeftSpineFib(n - 2, rt)).fork();
74			n -= 1;
75			}
76			int r = seqFib(n);
77			while (rt != null) {
78			if (rt.tryUnfork()) rt.compute(); else rt.helpJoin();
79			r += rt.number;
80			rt = rt.next;
81			}
82			number = r;
83			}
84			}
85
86			// Sequential version for arguments less than threshold
87			static int seqFib(int n) {
88	jsr166	1.2	if (n <= 1)
89	dl	1.1	return n;
90	jsr166	1.2	else
91	dl	1.1	return seqFib(n-1) + seqFib(n-2);
92			}
93	jsr166	1.2
94	dl	1.1	}