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import java.util.concurrent.*;
class FibJavaForkJoin extends RecursiveTask<Integer> {
static int repeat = 10;
static int size = 40;
static int cutOff = 10;
static int fib(int n) {
if (n <= 1) return n;
else return fib(n - 1) + fib(n - 2);
}
static int fibp(int n) {
if (n <= cutOff) return fib(n);
ForkJoinTask<Integer> t = new FibJavaForkJoin(n - 1).fork();
int r2 = fibp(n - 2);
return t.join() + r2;
}
int arg;
FibJavaForkJoin(int n) {
arg = n;
}
protected Integer compute() {
return fibp(arg);
}
static int doit(ForkJoinPool p) {
return p.invoke(new FibJavaForkJoin(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.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();
System.out.println(" bench: fib_java_forkjoin");
System.out.println(" size: " + size);
System.out.println(" cutoff: " + cutOff);
System.out.println(" results:");
rep(p);
}
}
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