Uploaded image for project: 'JDK'
  1. JDK
  2. JDK-4500388

Calling Thread.sleep with small argument affects system clock on windows

    Details

    • Type: Bug
    • Status: Closed
    • Priority: P4
    • Resolution: Fixed
    • Affects Version/s: 1.3.0, 1.3.1, 1.3.1_04, 1.4.0, 1.4.1, 5.0u4
    • Fix Version/s: 1.3.1_04
    • Component/s: hotspot
    • Subcomponent:
    • Resolved In Build:
      04
    • CPU:
      x86
    • OS:
      windows_nt, windows_2000, windows_xp

      Backports

        Description

        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

          Attachments

            Issue Links

              Activity

                People

                • Assignee:
                  minqi Yumin Qi
                  Reporter:
                  mimiali Mir Ali (Inactive)
                • Votes:
                  0 Vote for this issue
                  Watchers:
                  2 Start watching this issue

                  Dates

                  • Created:
                    Updated:
                    Resolved:
                    Imported:
                    Indexed: