In our system, we know more or less how long a thread should run for, worst
case scenario. If it takes longer than that, then something is wrong, and we would like to kill it. However, unless the thread is doing I/O or sleeping, calling the interrupt() method does not kill the thread. It changes the interrupt status, but if something is wrong, then the interrupted status cannot be checked. Throwing some kind of unexpected exception (such as InterruptedException) would cause the thread to unwind all the way up to where we can clean it up.