test/loops/DynamicLeftSpineFib.java

/*
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

import java.util.*;
import java.util.concurrent.*;

public final class DynamicLeftSpineFib extends RecursiveAction {

    static long lastStealCount;

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

        for (int reps = 0; reps < 2; ++reps) {
            ForkJoinPool g = (procs == 0) ? ForkJoinPool.commonPool() :
                new ForkJoinPool(procs);
            lastStealCount = g.getStealCount();
            for (int i = 0; i < 20; ++i) {
                test(g, num);
            }
            System.out.println(g);
            if (g != ForkJoinPool.commonPool()) {
                g.shutdown();
                if (!g.awaitTermination(10, TimeUnit.SECONDS))
                    throw new Error();
            }
            Thread.sleep(1000);
        }
    }

    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("DLSFib " + 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 void compute() {
        number = fib(number);
    }

    static final int fib(int n) {
        if (n <= 1)
            return n;
        int r = 0;
        DynamicLeftSpineFib rt = null;
        while (getSurplusQueuedTaskCount() <= 3) {
            int m = n - 2;
            if (m <= 1)
                r += m;
            else
                (rt = new DynamicLeftSpineFib(m, rt)).fork();
            if (--n <= 1)
                break;
        }
        r += n <= 1 ? n : seqFib(n);
        if (rt != null)
            r += collectRights(rt);
        return r;
    }

    static final int collectRights(DynamicLeftSpineFib rt) {
        int r = 0;
        while (rt != null) {
            DynamicLeftSpineFib rn = rt.next;
            rt.next = null;
            if (rt.tryUnfork())
                r += fib(rt.number);
            else {
                rt.join();
                r += rt.number;
            }
            rt = rn;
        }
        return r;
    }

    /** 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:	1.18
Committed:	Sat Sep 12 19:09:00 2015 UTC (8 years, 8 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.17:	+1 -2 lines
Log Message:	style nits
#	User	Rev	Content
1	jsr166	1.14	/*
2			* Written by Doug Lea with assistance from members of JCP JSR-166
3			* Expert Group and released to the public domain, as explained at
4			* http://creativecommons.org/publicdomain/zero/1.0/
5			*/
6
7	jsr166	1.15	import java.util.*;
8	dl	1.10	import java.util.concurrent.*;
9	dl	1.1
10			public final class DynamicLeftSpineFib extends RecursiveAction {
11
12			static long lastStealCount;
13	jsr166	1.11
14	dl	1.1	public static void main(String[] args) throws Exception {
15			int procs = 0;
16	dl	1.10	int num = 45;
17	dl	1.1	try {
18			if (args.length > 0)
19			procs = Integer.parseInt(args[0]);
20			if (args.length > 1)
21			num = Integer.parseInt(args[1]);
22			}
23			catch (Exception e) {
24	dl	1.7	System.out.println("Usage: java DynamicLeftSpineFib <threads> <number> [<sequntialThreshold>]");
25	dl	1.1	return;
26			}
27
28			for (int reps = 0; reps < 2; ++reps) {
29	dl	1.17	ForkJoinPool g = (procs == 0) ? ForkJoinPool.commonPool() :
30	dl	1.1	new ForkJoinPool(procs);
31			lastStealCount = g.getStealCount();
32	dl	1.10	for (int i = 0; i < 20; ++i) {
33	dl	1.1	test(g, num);
34			}
35			System.out.println(g);
36	dl	1.17	if (g != ForkJoinPool.commonPool()) {
37			g.shutdown();
38			if (!g.awaitTermination(10, TimeUnit.SECONDS))
39			throw new Error();
40			}
41	dl	1.10	Thread.sleep(1000);
42	dl	1.1	}
43			}
44
45			static void test(ForkJoinPool g, int num) throws Exception {
46			int ps = g.getParallelism();
47			long start = System.currentTimeMillis();
48			DynamicLeftSpineFib f = new DynamicLeftSpineFib(num, null);
49			g.invoke(f);
50			long time = System.currentTimeMillis() - start;
51	dl	1.7	double secs = ((double)time) / 1000.0;
52	dl	1.1	long result = f.getAnswer();
53	dl	1.7	System.out.print("DLSFib " + num + " = " + result);
54	dl	1.1	System.out.printf("\tTime: %7.3f", secs);
55			long sc = g.getStealCount();
56			long ns = sc - lastStealCount;
57			lastStealCount = sc;
58			System.out.printf(" Steals/t: %5d", ns/ps);
59			System.out.printf(" Workers: %8d", g.getPoolSize());
60			System.out.println();
61			}
62
63			// Initialized with argument; replaced with result
64			int number;
65			DynamicLeftSpineFib next;
66
67	jsr166	1.11	DynamicLeftSpineFib(int n, DynamicLeftSpineFib nxt) {
68			number = n; next = nxt;
69	dl	1.1	}
70
71			int getAnswer() {
72			return number;
73			}
74	dl	1.17
75	jsr166	1.11	public void compute() {
76			number = fib(number);
77	dl	1.10	}
78	dl	1.1
79	dl	1.10	static final int fib(int n) {
80			if (n <= 1)
81			return n;
82			int r = 0;
83			DynamicLeftSpineFib rt = null;
84			while (getSurplusQueuedTaskCount() <= 3) {
85			int m = n - 2;
86	dl	1.17	if (m <= 1)
87	dl	1.10	r += m;
88	dl	1.17	else
89			(rt = new DynamicLeftSpineFib(m, rt)).fork();
90			if (--n <= 1)
91	dl	1.10	break;
92			}
93	dl	1.17	r += n <= 1 ? n : seqFib(n);
94	dl	1.10	if (rt != null)
95			r += collectRights(rt);
96			return r;
97			}
98	jsr166	1.11
99	dl	1.10	static final int collectRights(DynamicLeftSpineFib rt) {
100			int r = 0;
101			while (rt != null) {
102			DynamicLeftSpineFib rn = rt.next;
103			rt.next = null;
104			if (rt.tryUnfork())
105			r += fib(rt.number);
106			else {
107			rt.join();
108	dl	1.1	r += rt.number;
109			}
110	dl	1.10	rt = rn;
111	dl	1.1	}
112	dl	1.10	return r;
113	dl	1.1	}
114
115	jsr166	1.18	/** Sequential version for arguments less than threshold */
116	dl	1.10	static final int seqFib(int n) { // unroll left only
117			int r = 1;
118			do {
119			int m = n - 2;
120			r += m <= 1 ? m : seqFib(m);
121			} while (--n > 1);
122			return r;
123	dl	1.1	}
124	jsr166	1.8
125	dl	1.7	}