private static ExecutorService newFixedDiscardingThreadPool(final int nThreads, final String prefix) {
        return new ThreadPoolExecutor(nThreads, nThreads,
                0L, TimeUnit.MILLISECONDS,
                new LinkedBlockingQueue<>(),
                new RxThreadFactory(prefix),
                DISCARD_POLICY);
    }
Provide an executor service with a fixed number of threads and an unbounded queue. If the
service is shutdown while tasks are still queued, jobs will be silently discarded.
main/src/main/java/cgeo/geocaching/utils/AndroidRxUtils.java