test/loops/LeftSpineFib.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 LeftSpineFib extends RecursiveAction {

    // Performance-tuning constant:
    static int sequentialThreshold;
    static long lastStealCount;

    public static void main(String[] args) throws Exception {
        int procs = 0;
        int num = 45;
        sequentialThreshold = 2;
        try {
            if (args.length > 0)
                procs = Integer.parseInt(args[0]);
            if (args.length > 1)
                num = Integer.parseInt(args[1]);
            if (args.length > 2)
                sequentialThreshold = Integer.parseInt(args[2]);
        }
        catch (Exception e) {
            System.out.println("Usage: java LeftSpineFib <threads> <number> [<sequntialThreshold>]");
            return;
        }

        for (int reps = 0; reps < 2; ++reps) {
            ForkJoinPool g = (procs == 0) ? new ForkJoinPool() :
                new ForkJoinPool(procs);
            //            g.setMaintainsParallelism(false);
            lastStealCount = g.getStealCount();
            for (int i = 0; i < 20; ++i) {
                test(g, num);
                Thread.sleep(50);
            }
            System.out.println(g);
            g.shutdown();
            if (!g.awaitTermination(8, TimeUnit.SECONDS)) {
                System.out.println(g);
                throw new Error();
            }
            g = null;
            //            System.gc();
            Thread.sleep(500);
        }
    }

    static void test(ForkJoinPool g, int num) throws Exception {
        int ps = g.getParallelism();
        long start = System.currentTimeMillis();
        LeftSpineFib f = new LeftSpineFib(num, null);
        g.invoke(f);
        long time = System.currentTimeMillis() - start;
        double secs = ((double)time) / 1000.0;
        long result = f.getAnswer();
        System.out.print("JLSFib " + 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.getRunningThreadCount());
        System.out.printf(" Workers: %8d", g.getPoolSize());
        System.out.println();
    }

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

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

    int getAnswer() {
        return number;
    }

    public final void compute() {
        int n = number;
        if (n > 1) {
            LeftSpineFib rt = null;
            int r = 0;
            while (n > sequentialThreshold) {
                int m = n - 2;
                if (m <= 1)
                    r += m;
                else
                    (rt = new LeftSpineFib(m, rt)).fork();
                n -= 1;
            }
            r += n <= 1 ? n : seqFib(n);
            if (rt != null)
                r += collectRights(rt);
            number = r;
        }
    }

    static final int collectRights(LeftSpineFib rt) {
        int r = 0;
        while (rt != null) {
            LeftSpineFib rn = rt.next;
            rt.next = null;
            if (rt.tryUnfork()) rt.compute(); else rt.join();
            //            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:	1.6
Committed:	Thu Jan 15 18:34:19 2015 UTC (9 years, 4 months ago) by jsr166
Branch:	MAIN
Changes since 1.5:	+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 LeftSpineFib extends RecursiveAction {
11
12	// Performance-tuning constant:
13	static int sequentialThreshold;
14	static long lastStealCount;
15
16	public static void main(String[] args) throws Exception {
17	int procs = 0;
18	int num = 45;
19	sequentialThreshold = 2;
20	try {
21	if (args.length > 0)
22	procs = Integer.parseInt(args[0]);
23	if (args.length > 1)
24	num = Integer.parseInt(args[1]);
25	if (args.length > 2)
26	sequentialThreshold = Integer.parseInt(args[2]);
27	}
28	catch (Exception e) {
29	System.out.println("Usage: java LeftSpineFib <threads> <number> [<sequntialThreshold>]");
30	return;
31	}
32
33	for (int reps = 0; reps < 2; ++reps) {
34	ForkJoinPool g = (procs == 0) ? new ForkJoinPool() :
35	new ForkJoinPool(procs);
36	// g.setMaintainsParallelism(false);
37	lastStealCount = g.getStealCount();
38	for (int i = 0; i < 20; ++i) {
39	test(g, num);
40	Thread.sleep(50);
41	}
42	System.out.println(g);
43	g.shutdown();
44	if (!g.awaitTermination(8, TimeUnit.SECONDS)) {
45	System.out.println(g);
46	throw new Error();
47	}
48	g = null;
49	// System.gc();
50	Thread.sleep(500);
51	}
52	}
53
54	static void test(ForkJoinPool g, int num) throws Exception {
55	int ps = g.getParallelism();
56	long start = System.currentTimeMillis();
57	LeftSpineFib f = new LeftSpineFib(num, null);
58	g.invoke(f);
59	long time = System.currentTimeMillis() - start;
60	double secs = ((double)time) / 1000.0;
61	long result = f.getAnswer();
62	System.out.print("JLSFib " + num + " = " + result);
63	System.out.printf("\tTime: %7.3f", secs);
64	long sc = g.getStealCount();
65	long ns = sc - lastStealCount;
66	lastStealCount = sc;
67	System.out.printf(" Steals/t: %5d", ns/ps);
68	// System.out.printf(" Workers: %8d", g.getRunningThreadCount());
69	System.out.printf(" Workers: %8d", g.getPoolSize());
70	System.out.println();
71	}
72
73	// Initialized with argument; replaced with result
74	int number;
75	LeftSpineFib next;
76
77	LeftSpineFib(int n, LeftSpineFib nxt) { number = n; next = nxt; }
78
79	int getAnswer() {
80	return number;
81	}
82
83	public final void compute() {
84	int n = number;
85	if (n > 1) {
86	LeftSpineFib rt = null;
87	int r = 0;
88	while (n > sequentialThreshold) {
89	int m = n - 2;
90	if (m <= 1)
91	r += m;
92	else
93	(rt = new LeftSpineFib(m, rt)).fork();
94	n -= 1;
95	}
96	r += n <= 1 ? n : seqFib(n);
97	if (rt != null)
98	r += collectRights(rt);
99	number = r;
100	}
101	}
102
103	static final int collectRights(LeftSpineFib rt) {
104	int r = 0;
105	while (rt != null) {
106	LeftSpineFib rn = rt.next;
107	rt.next = null;
108	if (rt.tryUnfork()) rt.compute(); else rt.join();
109	// rt.join();
110	r += rt.number;
111	rt = rn;
112	}
113	return r;
114	}
115
116	// Sequential version for arguments less than threshold
117	static final int seqFib(int n) { // unroll left only
118	int r = 1;
119	do {
120	int m = n - 2;
121	r += m <= 1 ? m : seqFib(m);
122	} while (--n > 1);
123	return r;
124	}
125
126	}