Multithreading timers less than 10 ms causes Windows clock to run too fast.Compile the test case on JDK 1.3.0 and run on Windows 2000 Professional,Use an independent timer (like a kitchen timer) to measure the execution time of the program.

The 5 ms sleep causes a call to NTSetTimerResolution in the OS to set the timer to 1 ms resolution (in order to discriminate the passage of 5 ms).
 The multithreading of the timers is causing a problem.
 
 The problem is not observed in classic mode, or using the MS virtual machine.

 TESTCASEBEGIN
 /**
  * This class is meant to demonstrate an issue with the system time when 
running the HotSpot VM and sleeping for less than 10 ms. When it is run with the HotSpot VM, the system time will be off. The program will run for 10 system minutes, but when verifying with a stop watch, is took only 9 minutes and 50 seconds.
  * Steps to try this:
  * 1. Set a count-down timer to 10 minutes.
  * 2. At the same moment, run the application and start the count-down timer.
  * 3. At the moment the software stops, stop the timer. When the timer is 
       zero,it means that the system took 10 real minutes. When there is time           left on the timer, the system took less than 10 minutes.
+  * Another way to try this:
+  * 1. Remove the code where the "timer" is created so the application
+  *    will not stop after 10 minutes.
+  * 2. Set an external clock at exactly the same time as the computer clock.
+  * 3. Run the application.
+  * 4. After a couple of hours, compare the system clock with the external 
        clock.
+ Note that the system clock is a couple of minutes fast.
   */


 public class TestBase {
    public int launchThread(final int id, final int sleepTime) {
 
       // Create a new thread object
       Thread t = new Thread(new Runnable() {
                                public void run() {
                                   // Loop forever
                                   while (true) {
                                      // Print the ID
                                      System.out.print(""+id);
                                      // Do some processing
                                      for (int i=0; i<1000; i++) {
                                         for (int j=0; j<1000; j++) {
                            double x = (double)i * j / j + i - j * j;
                                        }
                                      }
               // Sleep for the amount specified in the sleep time
                                     
   try {
	Thread.currentThread().sleep(sleepTime);
                 }
                    catch (InterruptedException e) {
                                         ;
                                      }
                                   }
                                }
                             });
       // Start the thread
       t.start();
       return 0;
    }
 
    public static void main(String[] args) {
       // Create a Thread that will print the ms time every 30 seconds
       Thread timer = new Thread(new Runnable() {
                                    public void run() {
                                       // Print the begin time
                                       long start = System.currentTimeMillis();
                      System.out.println("Start time: " + start);
                                       try {
                                          // Sleep for 10 minutes
                                          Thread.currentThread().sleep(600000);
                                       }
                                       catch (InterruptedException e) {
                                          ;
                                       }
                                       // Print the current time
                  System.out.println("time: " +(System.currentTimeMillis() - start));
                                       System.exit(0);
                                    }
                                 });
       // Start the timer thread
       // Remove this line of code when it is not desired to stop the app after 10 minutes.
       timer.start();
 
       // Create a new test base object
       TestBase tb = new TestBase();
 
       // Launch a thread with a 5 ms sleep time
       tb.launchThread(1, 5);
 
       // Launch a thread with a 10 ms sleep time
       tb.launchThread(2, 10);
    }
 }
 
 
 
 
 
 TESTCASEEND