test/loops/TorusSpanningTree.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 jsr166y.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.concurrent.atomic.*;

/**
 * This is reworked version of one of the tests reported on in the
 * paper: Guojing Cong, Sreedhar Kodali, Sriram Krishnamoorty, Doug
 * Lea, Vijay Saraswat and Tong Wen, "Solving irregular graph problems
 * using adaptive work-stealing", ICPP, 2008.
 *
 * It runs the main batching algorithm discussed there for spanning
 * trees, for a simple regular torus graph, where each node is
 * connected to its left. right, up, and down neighbors.
 */
public class TorusSpanningTree {
    static final int NCPUS = Runtime.getRuntime().availableProcessors();

    // Dimensions for test runs.
    // graphs have side*side nodes, each with 4 neighbors
    static final int MIN_SIDE = 1000;
    static final int MAX_SIDE = 3000;
    static final int SIDE_STEP = 500;

    public static void main(String[] args) throws Exception {
        Random rng = new Random();
        int procs = NCPUS;
        try {
            if (args.length > 0)
                procs = Integer.parseInt(args[0]);
        }
        catch (Exception e) {
            System.out.println("Usage: java TorusSpanningTree <threads>");
            return;
        }
        System.out.println("Number of threads: " + procs);
        System.out.println("Printing nanosec per edge across replications");
        System.out.print("for Toruses with side lengths");
        System.out.printf(" from %5d to %5d step %5d\n",
                          MIN_SIDE, MAX_SIDE, SIDE_STEP);
        ForkJoinPool pool = new ForkJoinPool(procs);

        boolean checked = false;
        for (int side = MIN_SIDE; side <= MAX_SIDE; side += SIDE_STEP) {
            int n = side * side;
            Node[] graph = makeGraph(side);
            System.out.printf( "N:%9d", n);
            for (int j = 0; j < 8; ++j) {
                Node root = graph[rng.nextInt(n)];
                long start = System.nanoTime();
                pool.invoke(new Driver(root));
                long elapsed = System.nanoTime() - start;
                double nanosPerEdge = (double) elapsed / (4 * n);
                System.out.printf(" %7.2f", nanosPerEdge);
                if (!checked) {
                    checked = true;
                    checkSpanningTree(graph, root);
                }
                pool.invoke(new Resetter(graph, 0, graph.length));
            }
            graph = null;
            System.out.println();
        }
        System.out.println(pool);
        pool.shutdown();
    }

    static final class Node extends ForkJoinTask<Void> {
        final Node[] neighbors;
        Node parent;
        Node next;

        Node(Node[] nbrs) {
            neighbors = nbrs;
            parent = this;
        }

        /*
         * Traverse the list ("oldList") embedded across .next fields,
         * starting at this node, placing newly discovered neighboring
         * nodes in newList. If the oldList becomes exhausted, swap in
         * newList and continue. Otherwise, whenever the length of
         * newList exceeds current number of tasks in work-stealing
         * queue, push list onto queue.
         */

        static final int LOG_MAX_BATCH_SIZE = 7;

        /**
         * Since tasks are never joined, we bypass Recursive{Action,Task}
         * and just directly implement exec
         */
        public boolean exec() {
            int batchSize = 0; // computed lazily
            Node newList = null;
            int newLength = 0;
            Node oldList = this;
            Node par = parent;
            do {
                Node v = oldList;
                Node[] edges = v.neighbors;
                oldList = v.next;
                int nedges = edges.length;
                for (int k = 0; k < nedges; ++k) {
                    Node e = edges[k];
                    if (e != null &&
                        e.compareAndSetForkJoinTaskTag((short)0, (short)1)) {
                        e.parent = par;
                        e.next = newList;
                        newList = e;
                        if (batchSize == 0) {
                            int s = getQueuedTaskCount();
                            batchSize = ((s >= LOG_MAX_BATCH_SIZE) ?
                                         (1 << LOG_MAX_BATCH_SIZE) :
                                         (1 << s));
                        }
                        if (++newLength >= batchSize) {
                            newLength = 0;
                            batchSize = 0;
                            if (oldList == null)
                                oldList = newList;
                            else
                                newList.fork();
                            newList = null;
                        }
                    }
                }
                if (oldList == null) {
                    oldList = newList;
                    newList = null;
                    newLength = 0;
                }
            } while (oldList != null);
            return false;
        }

        // required abstract implementations for ForkJoinTask
        public final Void getRawResult() { return null; }
        protected final void setRawResult(Void mustBeNull) { }

        public void reset() {
            reinitialize();
            parent = this;
            next = null;
        }

    }

    static final class Driver extends RecursiveAction {
        final Node root;
        Driver(Node root) {
            this.root = root;
        }
        public void compute() {
            root.setForkJoinTaskTag((short)1);
            root.fork();
            helpQuiesce();
        }
    }

    static Node[] makeGraph(int sideLength) {
        int n = sideLength * sideLength;
        Node[] vs = new Node[n];
        for (int i = 0; i < n; ++i)
            vs[i] = new Node(new Node[4]);

        // connect each node to left, right, up, down neighbors
        int maxcol = n - sideLength;
        int col = 0;
        for (int i = 0; i < sideLength; ++i) {
            for (int j = 0; j < sideLength; ++j) {
                Node[] a = vs[col + j].neighbors;
                a[0] = vs[col + ((j < sideLength-1) ? (j+1) : 0)];
                a[1] = vs[col + ((j != 0) ? (j-1) : (sideLength-1))];
                a[2] = vs[j + ((i < sideLength-1) ? (col + sideLength) : 0)];
                a[3] = vs[j + ((i != 0) ? (col - sideLength) : maxcol)];
            }
            col += sideLength;
        }
        return vs;
    }

    static void resetAll(Node[] g) {
        for (int i = 0; i < g.length; ++i)
            g[i].reset();
    }

    // check that all nodes have parents, and no cycles
    static void checkSpanningTree(Node[] g, Node root) {
        int n = g.length;
        for (int i = 0; i < n; ++i) {
            Node v = g[i];
            Node p = v;
            int k = n;
            while (p != root) {
                if (p == null)
                    throw new RuntimeException("null parent");
                if (--k <= 0)
                    throw new RuntimeException("cycle");
                p = p.parent;
            }
            v.parent = root;
        }
    }

    static final class Resetter extends RecursiveAction {
        final Node[] g;
        final int lo, hi;
        Resetter(Node[] g, int lo, int hi) {
            this.g = g; this.lo = lo; this.hi = hi;
        }
        public void compute() {
            int mid = (lo + hi) >>> 1;
            if (mid == lo || getSurplusQueuedTaskCount() > 3) {
                for (int i = lo; i < hi; ++i)
                    g[i].reset();
            }
            else
                invokeAll(new Resetter(g, lo, mid), new Resetter(g, mid, hi));
        }
    }
}
Revision:	1.10
Committed:	Sat Sep 12 20:57:12 2015 UTC (8 years, 8 months ago) by jsr166
Branch:	MAIN
CVS Tags:	HEAD
Changes since 1.9:	+1 -1 lines
Log Message:	whitespace
#	User	Rev	Content
1	dl	1.1	/*
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	jsr166	1.8	* http://creativecommons.org/publicdomain/zero/1.0/
5	dl	1.1	*/
6
7			//import jsr166y.*;
8			import java.util.*;
9			import java.util.concurrent.*;
10			import java.util.concurrent.atomic.*;
11
12			/**
13			* This is reworked version of one of the tests reported on in the
14			* paper: Guojing Cong, Sreedhar Kodali, Sriram Krishnamoorty, Doug
15			* Lea, Vijay Saraswat and Tong Wen, "Solving irregular graph problems
16			* using adaptive work-stealing", ICPP, 2008.
17	jsr166	1.2	*
18	dl	1.1	* It runs the main batching algorithm discussed there for spanning
19			* trees, for a simple regular torus graph, where each node is
20			* connected to its left. right, up, and down neighbors.
21			*/
22			public class TorusSpanningTree {
23			static final int NCPUS = Runtime.getRuntime().availableProcessors();
24
25	jsr166	1.2	// Dimensions for test runs.
26	dl	1.1	// graphs have side*side nodes, each with 4 neighbors
27			static final int MIN_SIDE = 1000;
28			static final int MAX_SIDE = 3000;
29			static final int SIDE_STEP = 500;
30
31			public static void main(String[] args) throws Exception {
32			Random rng = new Random();
33			int procs = NCPUS;
34			try {
35			if (args.length > 0)
36			procs = Integer.parseInt(args[0]);
37			}
38			catch (Exception e) {
39			System.out.println("Usage: java TorusSpanningTree <threads>");
40			return;
41			}
42			System.out.println("Number of threads: " + procs);
43			System.out.println("Printing nanosec per edge across replications");
44			System.out.print("for Toruses with side lengths");
45	jsr166	1.2	System.out.printf(" from %5d to %5d step %5d\n",
46	dl	1.1	MIN_SIDE, MAX_SIDE, SIDE_STEP);
47			ForkJoinPool pool = new ForkJoinPool(procs);
48
49	dl	1.6	boolean checked = false;
50	dl	1.1	for (int side = MIN_SIDE; side <= MAX_SIDE; side += SIDE_STEP) {
51			int n = side * side;
52			Node[] graph = makeGraph(side);
53			System.out.printf( "N:%9d", n);
54			for (int j = 0; j < 8; ++j) {
55			Node root = graph[rng.nextInt(n)];
56			long start = System.nanoTime();
57			pool.invoke(new Driver(root));
58			long elapsed = System.nanoTime() - start;
59	jsr166	1.4	double nanosPerEdge = (double) elapsed / (4 * n);
60	jsr166	1.7	System.out.printf(" %7.2f", nanosPerEdge);
61	dl	1.6	if (!checked) {
62			checked = true;
63	dl	1.1	checkSpanningTree(graph, root);
64	dl	1.6	}
65			pool.invoke(new Resetter(graph, 0, graph.length));
66	dl	1.1	}
67	dl	1.9	graph = null;
68	dl	1.1	System.out.println();
69	jsr166	1.2	}
70	dl	1.6	System.out.println(pool);
71	jsr166	1.2	pool.shutdown();
72	dl	1.1	}
73
74			static final class Node extends ForkJoinTask<Void> {
75	jsr166	1.2	final Node[] neighbors;
76	dl	1.1	Node parent;
77			Node next;
78	jsr166	1.2
79	dl	1.1	Node(Node[] nbrs) {
80			neighbors = nbrs;
81			parent = this;
82			}
83
84			/*
85			* Traverse the list ("oldList") embedded across .next fields,
86			* starting at this node, placing newly discovered neighboring
87			* nodes in newList. If the oldList becomes exhausted, swap in
88			* newList and continue. Otherwise, whenever the length of
89			* newList exceeds current number of tasks in work-stealing
90			* queue, push list onto queue.
91			*/
92
93			static final int LOG_MAX_BATCH_SIZE = 7;
94
95			/**
96			* Since tasks are never joined, we bypass Recursive{Action,Task}
97			* and just directly implement exec
98			*/
99			public boolean exec() {
100			int batchSize = 0; // computed lazily
101			Node newList = null;
102			int newLength = 0;
103			Node oldList = this;
104			Node par = parent;
105			do {
106			Node v = oldList;
107			Node[] edges = v.neighbors;
108			oldList = v.next;
109			int nedges = edges.length;
110			for (int k = 0; k < nedges; ++k) {
111			Node e = edges[k];
112	jsr166	1.10	if (e != null &&
113	dl	1.9	e.compareAndSetForkJoinTaskTag((short)0, (short)1)) {
114	dl	1.1	e.parent = par;
115			e.next = newList;
116			newList = e;
117			if (batchSize == 0) {
118			int s = getQueuedTaskCount();
119	jsr166	1.3	batchSize = ((s >= LOG_MAX_BATCH_SIZE) ?
120	dl	1.1	(1 << LOG_MAX_BATCH_SIZE) :
121			(1 << s));
122			}
123			if (++newLength >= batchSize) {
124			newLength = 0;
125			batchSize = 0;
126			if (oldList == null)
127			oldList = newList;
128			else
129			newList.fork();
130			newList = null;
131			}
132			}
133			}
134			if (oldList == null) {
135			oldList = newList;
136			newList = null;
137			newLength = 0;
138			}
139			} while (oldList != null);
140			return false;
141			}
142
143			// required abstract implementations for ForkJoinTask
144			public final Void getRawResult() { return null; }
145			protected final void setRawResult(Void mustBeNull) { }
146
147			public void reset() {
148			reinitialize();
149			parent = this;
150			next = null;
151			}
152
153			}
154
155			static final class Driver extends RecursiveAction {
156			final Node root;
157	jsr166	1.2	Driver(Node root) {
158	dl	1.1	this.root = root;
159			}
160			public void compute() {
161	dl	1.9	root.setForkJoinTaskTag((short)1);
162	dl	1.1	root.fork();
163			helpQuiesce();
164			}
165			}
166
167			static Node[] makeGraph(int sideLength) {
168			int n = sideLength * sideLength;
169			Node[] vs = new Node[n];
170			for (int i = 0; i < n; ++i)
171			vs[i] = new Node(new Node[4]);
172
173			// connect each node to left, right, up, down neighbors
174			int maxcol = n - sideLength;
175			int col = 0;
176	jsr166	1.3	for (int i = 0; i < sideLength; ++i) {
177			for (int j = 0; j < sideLength; ++j) {
178	dl	1.1	Node[] a = vs[col + j].neighbors;
179	jsr166	1.3	a[0] = vs[col + ((j < sideLength-1) ? (j+1) : 0)];
180			a[1] = vs[col + ((j != 0) ? (j-1) : (sideLength-1))];
181			a[2] = vs[j + ((i < sideLength-1) ? (col + sideLength) : 0)];
182			a[3] = vs[j + ((i != 0) ? (col - sideLength) : maxcol)];
183	dl	1.1	}
184			col += sideLength;
185			}
186			return vs;
187			}
188
189			static void resetAll(Node[] g) {
190			for (int i = 0; i < g.length; ++i)
191			g[i].reset();
192			}
193
194			// check that all nodes have parents, and no cycles
195			static void checkSpanningTree(Node[] g, Node root) {
196			int n = g.length;
197			for (int i = 0; i < n; ++i) {
198			Node v = g[i];
199			Node p = v;
200			int k = n;
201			while (p != root) {
202			if (p == null)
203			throw new RuntimeException("null parent");
204			if (--k <= 0)
205			throw new RuntimeException("cycle");
206			p = p.parent;
207			}
208			v.parent = root;
209			}
210			}
211	jsr166	1.2
212	dl	1.6	static final class Resetter extends RecursiveAction {
213			final Node[] g;
214			final int lo, hi;
215			Resetter(Node[] g, int lo, int hi) {
216			this.g = g; this.lo = lo; this.hi = hi;
217			}
218			public void compute() {
219			int mid = (lo + hi) >>> 1;
220			if (mid == lo \|\| getSurplusQueuedTaskCount() > 3) {
221			for (int i = lo; i < hi; ++i)
222			g[i].reset();
223			}
224			else
225			invokeAll(new Resetter(g, lo, mid), new Resetter(g, mid, hi));
226			}
227			}
228	dl	1.1	}