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import java.util.concurrent.*;
class MandelbrotJavaForkJoin extends RecursiveTask<Integer> {
static int repeat = 10;
static int size = 2048;
static int cutOff = 8;
static final double x_base = -2.0;
static final double y_base = 1.25;
static final double side = 2.5;
static final int maxCount = 1024;
static double delta; // = side / size
static char image[];
static int loopV(int x, int y, int w, int h)
{
int iterations = 0;
int i, j, count;
double c_re, c_im, z_re, z_im, z_re_sq, z_im_sq, re, im;
for (i = 0; i < h; i++) {
c_im = y_base - delta * (i + y);
for (j = 0; j < w; j++) {
c_re = x_base + delta * (j + x);
z_re = c_re;
z_im = c_im;
for (count = 0; count < maxCount; count++) {
z_re_sq = z_re * z_re;
z_im_sq = z_im * z_im;
if (z_re_sq + z_im_sq > 4.0) {
image[j + x + size * (i + y)] = 1;
break;
}
re = z_re_sq - z_im_sq + c_re;
im = 2.0 * z_re * z_im + c_im;
z_re = re;
z_im = im;
}
iterations += count;
}
}
return iterations;
}
static int mandelbrot(int x, int y, int w, int h)
{
if (w <= cutOff && h <= cutOff) {
return loopV(x, y, w, h);
} else if (w >= h) {
int w2 = w / 2;
ForkJoinTask<Integer> t =
new MandelbrotJavaForkJoin(x + w2, y, w - w2, h).fork();
int r = mandelbrot(x, y, w2, h);
return r + t.join();
} else {
int h2 = h / 2;
ForkJoinTask<Integer> t =
new MandelbrotJavaForkJoin(x, y + h2, w, h - h2).fork();
int r = mandelbrot(x, y, w, h2);
return r + t.join();
}
}
int arg_x, arg_y, arg_w, arg_h;
MandelbrotJavaForkJoin(int x, int y, int w, int h) {
arg_x = x;
arg_y = y;
arg_w = w;
arg_h = h;
}
protected Integer compute() {
return mandelbrot(arg_x, arg_y, arg_w, arg_h);
}
static int doit(ForkJoinPool p) {
return p.invoke(new MandelbrotJavaForkJoin(0, 0, size, size));
}
static void rep(ForkJoinPool p) {
for (int i = 0; i < repeat; i++) {
long t1 = System.currentTimeMillis();
int r = doit(p);
long t2 = System.currentTimeMillis();
/*
System.err.println("P1\n" + size + " " + size);
for (int i = 0; i < size * size; i++)
System.err.print(image[i] + 0);
*/
System.out.println(" - {result: " + r + ", time: "
+ (double)(t2 - t1) / 1000.0 + "}");
}
}
public static void main(String[] args) {
if (args.length > 0) repeat = Integer.parseInt(args[0]);
if (args.length > 1) size = Integer.parseInt(args[1]);
if (args.length > 2) cutOff = Integer.parseInt(args[2]);
String nprocs = System.getenv("NPROCS");
ForkJoinPool p = nprocs != null
? new ForkJoinPool(Integer.parseInt(nprocs))
: new ForkJoinPool();
delta = side / size;
image = new char[size * size];
System.out.println(" bench: mandelbrot_java_forkjoin");
System.out.println(" size: " + size);
System.out.println(" cutoff: " + cutOff);
System.out.println(" results:");
rep(p);
}
}
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