FULL PRODUCT VERSION :
java version "1.8.0_102"
Java(TM) SE Runtime Environment (build 1.8.0_102-b14)
Java HotSpot(TM) 64-Bit Server VM (build 25.102-b14, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux ubdev 3.16.0-77-generic #99~14.04.1-Ubuntu SMP Tue Jun 28 19:17:10 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

A DESCRIPTION OF THE PROBLEM :
The Timer class has cancel() method, which "Terminates this timer, discarding any currently scheduled tasks.".

What this method does internally is the following:

   public void cancel() {
        synchronized(queue) {
            thread.newTasksMayBeScheduled = false;
            queue.clear();
            queue.notify(); // In case queue was already empty.
        }
    }

This looks all fine and matches the documentation. However, note that the Timer never joins its thread (which is a member of type TimerThread).

There is no way for a user of the Timer class to ensure that the thread it starts goes away. The Timer class should provide a method like join() to ensure that the thread is done.






STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Start a timer (give it a name), call cancel, print all the threads running

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
the threads listed should not include the Timer thread created
ACTUAL -
it sometimes includes the Time thread created

REPRODUCIBILITY :
This bug can be reproduced rarely.