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) ? new ForkJoinPool() :
                new ForkJoinPool(procs);
            lastStealCount = g.getStealCount();
            for (int i = 0; i < 20; ++i) {
                test(g, num);
            }
            System.out.println(g);
            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;
            n -= 1;
            if (m <= 1) {
                r += m;
                if (n > 1) {
                    r += n - 2;
                    n -= 1;
                }
                break;
            }
            (rt = new DynamicLeftSpineFib(m, rt)).fork();
        }
        if (n <= 1)
            r += n;
        else
            r += seqFib(n - 2) + fib(n - 1);
        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:	1.15
Committed:	Wed Dec 31 17:00:58 2014 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.14:	+1 -3 lines
Log Message:	lexicographic import order
#	Content
1	/*
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	import java.util.*;
8	import java.util.concurrent.*;
9
10	public final class DynamicLeftSpineFib extends RecursiveAction {
11
12	static long lastStealCount;
13
14	public static void main(String[] args) throws Exception {
15	int procs = 0;
16	int num = 45;
17	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	System.out.println("Usage: java DynamicLeftSpineFib <threads> <number> [<sequntialThreshold>]");
25	return;
26	}
27
28
29	for (int reps = 0; reps < 2; ++reps) {
30	ForkJoinPool g = (procs == 0) ? new ForkJoinPool() :
31	new ForkJoinPool(procs);
32	lastStealCount = g.getStealCount();
33	for (int i = 0; i < 20; ++i) {
34	test(g, num);
35	}
36	System.out.println(g);
37	g.shutdown();
38	if (!g.awaitTermination(10, TimeUnit.SECONDS))
39	throw new Error();
40	Thread.sleep(1000);
41	}
42	}
43
44	static void test(ForkJoinPool g, int num) throws Exception {
45	int ps = g.getParallelism();
46	long start = System.currentTimeMillis();
47	DynamicLeftSpineFib f = new DynamicLeftSpineFib(num, null);
48	g.invoke(f);
49	long time = System.currentTimeMillis() - start;
50	double secs = ((double)time) / 1000.0;
51	long result = f.getAnswer();
52	System.out.print("DLSFib " + num + " = " + result);
53	System.out.printf("\tTime: %7.3f", secs);
54	long sc = g.getStealCount();
55	long ns = sc - lastStealCount;
56	lastStealCount = sc;
57	System.out.printf(" Steals/t: %5d", ns/ps);
58	System.out.printf(" Workers: %8d", g.getPoolSize());
59	System.out.println();
60	}
61
62
63	// Initialized with argument; replaced with result
64	int number;
65	DynamicLeftSpineFib next;
66
67	DynamicLeftSpineFib(int n, DynamicLeftSpineFib nxt) {
68	number = n; next = nxt;
69	}
70
71	int getAnswer() {
72	return number;
73	}
74	public void compute() {
75	number = fib(number);
76	}
77
78	static final int fib(int n) {
79	if (n <= 1)
80	return n;
81	int r = 0;
82	DynamicLeftSpineFib rt = null;
83	while (getSurplusQueuedTaskCount() <= 3) {
84	int m = n - 2;
85	n -= 1;
86	if (m <= 1) {
87	r += m;
88	if (n > 1) {
89	r += n - 2;
90	n -= 1;
91	}
92	break;
93	}
94	(rt = new DynamicLeftSpineFib(m, rt)).fork();
95	}
96	if (n <= 1)
97	r += n;
98	else
99	r += seqFib(n - 2) + fib(n - 1);
100	if (rt != null)
101	r += collectRights(rt);
102	return r;
103	}
104
105	static final int collectRights(DynamicLeftSpineFib rt) {
106	int r = 0;
107	while (rt != null) {
108	DynamicLeftSpineFib rn = rt.next;
109	rt.next = null;
110	if (rt.tryUnfork())
111	r += fib(rt.number);
112	else {
113	rt.join();
114	r += rt.number;
115	}
116	rt = rn;
117	}
118	return r;
119	}
120
121	// Sequential version for arguments less than threshold
122	static final int seqFib(int n) { // unroll left only
123	int r = 1;
124	do {
125	int m = n - 2;
126	r += m <= 1 ? m : seqFib(m);
127	} while (--n > 1);
128	return r;
129	}
130
131	}