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Unfortunately, the stop() method incorrectly uses the Thread.getState() method to check whether the thread is blocked and has not terminated before delivering the notification. Using the Thread.getState() method for synchronization control, such as checking whether a thread is blocked on a wait, is inappropriate. Java Virtual Machines (JVMs) are permitted to implement blocking using spin-waiting; consequently, a thread can be blocked without entering the WAITING or TIMED_WAITING state [Goetz 2006a2006]. Because the thread may never enter the WAITING state, the stop() method might fail to terminate the thread.
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Relying on the Thread class's sleep(), yield(), and getState() methods for synchronization control can cause unexpected behavior.
Bibliography
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