}
    }


    private static void waitForQueryThreads ( QueryThread q1x, QueryThread q20 ) {
        interruptThreadSafely(q1x);
        joinThread(q1x);
        interruptThreadSafely(q20);
        joinThread(q20);
    }


    private static void interruptThreadSafely ( QueryThread thread ) {
        try {
            thread.interrupt();
        }