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OutOfMemoryError - why waiting for a thread will not collect garbage?

This simple code example demonstrates the problem. I create ArrayBlockingQueueand a thread waiting for data in this queue using take(). After the cycle is completed, theoretically, both the queue and the stream can be garbage collected, but in practice I will soon get it OutOfMemoryError. What prevents it from being GC'd, and how can it be fixed?

/**
 * Produces out of memory exception because the thread cannot be garbage
 * collected.
 */
@Test
public void checkLeak() {
    int count = 0;
    while (true) {

        // just a simple demo, not useful code.
        final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<Integer>(2);
        final Thread t = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    abq.take();
                } catch (final InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
        t.start();

        // perform a GC once in a while
        if (++count % 1000 == 0) {
            System.out.println("gc");
            // this should remove all the previously created queues and threads
            // but it does not
            System.gc();
        }
    }
}

I am using Java 1.6.0.

UPDATE: execute GC after several iterations, but this does not help.

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7 answers

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while (true) {
    // just a simple demo, not useful code.
    // 0 0 - the first number is thread reference count, the second is abq ref count
    final ArrayBlockingQueue<Integer> abq = new ArrayBlockingQueue<Integer>(2);
    // 0 1
    final Thread t = new Thread(new Runnable() {
        @Override
        public void run() {
            try {
                abq.take();
                // 2 2
            } catch (final InterruptedException e) {
                e.printStackTrace();
            }
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    });
    // 1 1
    t.start();
    // 2 2 (because the run calls abq.take)
    // after end of loop
    // 1 1 - each created object reference count is decreased
}

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