How to interrupt BlockingQueue?

Question

BlockingQueue.put can throw InterruptedException. How can I cause the queue to be interrupting by throwing this exception?

ArrayBlockingQueue<Param> queue = new ArrayBlockingQueue<Param>(NUMBER_OF_MEMBERS);
...
try {
    queue.put(param);
} catch (InterruptedException e) {
    Log.w(TAG, "put Interrupted", e);
}
...
// how can I queue.notify?

Answer 1

You need to interrupt the thread that is calling the queue.put(...);. The put(...); call is doing a wait() on some internal condition and if the thread which is calling the put(...) gets interrupted, the wait(...) call will throw InterruptedException which is passed on by the put(...);

// interrupt a thread which causes the put() to throw
thread.interrupt();

To get the thread you can either store it when it is created:

Thread workerThread = new Thread(myRunnable);
...
workerThread.interrupt();

or you can use the Thread.currentThread() method call and store it somewhere for others to use to interrupt.

public class MyRunnable implements Runnable {
     public Thread myThread;
     public void run() {
         myThread = Thread.currentThread();
         ...
     }
     public void interruptMe() {
         myThread.interrupt();
     }
}

Lastly, it is a good pattern when you catch InterruptedException to immediately re-interrupt the thread because when the InterruptedException is thrown, the interrupt status on the thread is cleared.

try {
    queue.put(param);
} catch (InterruptedException e) {
    // immediately re-interrupt the thread
    Thread.currentThread().interrupt();
    Log.w(TAG, "put Interrupted", e);
    // maybe we should stop the thread here
}