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:	1.16
Committed:	Thu Jan 15 18:34:19 2015 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.15:	+0 -2 lines
Log Message:	delete extraneous blank lines
#	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	for (int reps = 0; reps < 2; ++reps) {
29	ForkJoinPool g = (procs == 0) ? new ForkJoinPool() :
30	new ForkJoinPool(procs);
31	lastStealCount = g.getStealCount();
32	for (int i = 0; i < 20; ++i) {
33	test(g, num);
34	}
35	System.out.println(g);
36	g.shutdown();
37	if (!g.awaitTermination(10, TimeUnit.SECONDS))
38	throw new Error();
39	Thread.sleep(1000);
40	}
41	}
42
43	static void test(ForkJoinPool g, int num) throws Exception {
44	int ps = g.getParallelism();
45	long start = System.currentTimeMillis();
46	DynamicLeftSpineFib f = new DynamicLeftSpineFib(num, null);
47	g.invoke(f);
48	long time = System.currentTimeMillis() - start;
49	double secs = ((double)time) / 1000.0;
50	long result = f.getAnswer();
51	System.out.print("DLSFib " + num + " = " + result);
52	System.out.printf("\tTime: %7.3f", secs);
53	long sc = g.getStealCount();
54	long ns = sc - lastStealCount;
55	lastStealCount = sc;
56	System.out.printf(" Steals/t: %5d", ns/ps);
57	System.out.printf(" Workers: %8d", g.getPoolSize());
58	System.out.println();
59	}
60
61	// Initialized with argument; replaced with result
62	int number;
63	DynamicLeftSpineFib next;
64
65	DynamicLeftSpineFib(int n, DynamicLeftSpineFib nxt) {
66	number = n; next = nxt;
67	}
68
69	int getAnswer() {
70	return number;
71	}
72	public void compute() {
73	number = fib(number);
74	}
75
76	static final int fib(int n) {
77	if (n <= 1)
78	return n;
79	int r = 0;
80	DynamicLeftSpineFib rt = null;
81	while (getSurplusQueuedTaskCount() <= 3) {
82	int m = n - 2;
83	n -= 1;
84	if (m <= 1) {
85	r += m;
86	if (n > 1) {
87	r += n - 2;
88	n -= 1;
89	}
90	break;
91	}
92	(rt = new DynamicLeftSpineFib(m, rt)).fork();
93	}
94	if (n <= 1)
95	r += n;
96	else
97	r += seqFib(n - 2) + fib(n - 1);
98	if (rt != null)
99	r += collectRights(rt);
100	return r;
101	}
102
103	static final int collectRights(DynamicLeftSpineFib rt) {
104	int r = 0;
105	while (rt != null) {
106	DynamicLeftSpineFib rn = rt.next;
107	rt.next = null;
108	if (rt.tryUnfork())
109	r += fib(rt.number);
110	else {
111	rt.join();
112	r += rt.number;
113	}
114	rt = rn;
115	}
116	return r;
117	}
118
119	// Sequential version for arguments less than threshold
120	static final int seqFib(int n) { // unroll left only
121	int r = 1;
122	do {
123	int m = n - 2;
124	r += m <= 1 ? m : seqFib(m);
125	} while (--n > 1);
126	return r;
127	}
128
129	}