I am having a problem with the ScheduledExecutorService in java (I didn't face this problem a couple of days back is what makes it strange for me). Please find the code below and the console output. The delay between executing the task repeatedly is 1 ms so I should ideally be reaching the count of 1000 every second (give or take a few milliseconds) but this is just not happening. Please help..
CODE:
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.TimeUnit;
public class SchedulerTest {
private static final ScheduledExecutorService executor = Executors.newScheduledThreadPool(2);
static DateFormat df= new SimpleDateFormat("dd-MMM-yyyy HH:mm:ss.SSS");
private static class TestRunnable1 implements Runnable{
private int count=0;
@Override
public void run() {
count++;
if(count1 % 1000==0){
System.out.println(count1+" "+df.format(Calendar.getInstance().getTime()));
}
}
}
public static void main(String[] args){
Runnable localService = new TestRunnable1();
try{
executor.scheduleWithFixedDelay(localService, 0, 1, TimeUnit.MILLISECONDS);
}catch(Exception e){
e.printStackTrace();
}
}
}
CONSOLE OUTPUT
1000 13-Mar-2013 14:43:54.477
2000 13-Mar-2013 14:44:10.296
3000 13-Mar-2013 14:44:26.381
4000 13-Mar-2013 14:44:42.621
5000 13-Mar-2013 14:44:55.907
6000 13-Mar-2013 14:44:58.516
7000 13-Mar-2013 14:45:05.896
8000 13-Mar-2013 14:45:10.292
9000 13-Mar-2013 14:45:15.129
10000 13-Mar-2013 14:45:18.187
You want to use ScheduledExecutorService#scheduleAtFixedRate rather than ScheduledExecutorService#scheduleWithFixedDelay.
If you schedule with a fixed delay, then 1 ms must elapse between the time that the last execution completed and the time that the next execution begins. So the wall-clock time that it takes to complete 1000 iterations will be, at a minimum, 1 second plus the execution time of the thousand iterations.