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package primefactors;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;
import java.util.logging.Level;
import java.util.logging.Logger;
public class ThreadedCount {
public static void main(String...args) throws InterruptedException, ExecutionException {
final int max = 1000000;
}
public static int findPrimes(final int max) {
try {
final int procs = Runtime.getRuntime().availableProcessors();
ExecutorService pool = Executors.newFixedThreadPool(procs);
System.out.println("using " + procs + " processors");
ArrayList> tasks = new ArrayList>();
for (int i = 0; i < procs; i++) {
final int n = i;
tasks.add(new Callable() {
public Integer call() throws Exception {
return findPrimes(max, procs, n);
}
});
}
int total = 0;
List> results = pool.invokeAll(tasks);
for (Future result : results) {
total += result.get();
System.out.println("result = " + result.get());
}
System.out.println("total = " + total);
try {
pool.shutdown();
} catch (Exception ex) {
ex.printStackTrace();
}
return total;
} catch (Exception ex) {
Logger.getLogger(ThreadedCount.class.getName()).log(Level.SEVERE, null, ex);
return -1;
}
}
private static int findPrimes(int n, int procs, int offset) {
int j;
double limit;
int numprimes = 0;
int i = 3+offset*2;
while(i <= n) {
boolean isPrime = true;
limit = Math.ceil(Math.sqrt(i)) + 1;
j = 3;
while(j < limit) {
if(i % j == 0) {
isPrime = false;
break;
}
j+=2;
}
i+=procs*2;
if(!isPrime) {
continue;
}
if(isPrime) {
numprimes++;
}
}
return numprimes;
}
}