void execute() {
      synchronized (runnables) {
        if (executed) {
          return;
        }
        executed = true;
      }

      while (!runnables.isEmpty()) {
        runnables.poll().execute();
      }
    }

    private static class RunnableExecutorPair {
      final Runnable runnable;
      final Executor executor;

      RunnableExecutorPair(Runnable runnable, Executor executor) {

            log.info("Removed {} idle connections from pool", toRemoveCount);
        }
    }

    /**
     * Set the maximum pool size
     * @param size the maximum number of connections in the pool
     */
    public void setMaxPoolSize(int size) {
        if (size <= 0) {
            throw new IllegalArgumentException("Pool size must be positive");
        }
        this.maxPoolSize = size;

  }

  void checkEmpty(BlockingQueue<?> q) {
    try {
      assertTrue(q.isEmpty());
      assertEquals(0, q.size());
      assertThat(q.peek()).isNull();
      assertThat(q.poll()).isNull();
      assertThat(q.poll(0, MILLISECONDS)).isNull();
      assertEquals("[]", q.toString());
      assertThat(q.toArray()).isEmpty();
      assertFalse(q.iterator().hasNext());
      try {
        q.element();

      while (true) {
        Future<T> f = futureQueue.poll();
        if (f == null) {
          if (ntasks > 0) {
            --ntasks;
            futures.add(submitAndAddQueueListener(executorService, it.next(), futureQueue));
            ++active;
          } else if (active == 0) {
            break;
          } else if (timed) {
            f = futureQueue.poll(timeoutNanos, TimeUnit.NANOSECONDS);

            .removalListener(listener)
            .ticker(ticker)
            .build();
    cache.put(1, 1);
    ticker.advance(10, MINUTES);
    cache.invalidateAll();

    assertThat(listener.poll().getCause()).isEqualTo(RemovalCause.EXPIRED);
  }

  private void runRemovalScheduler(
      LoadingCache<String, Integer> cache,
      CountingRemovalListener<String, Integer> removalListener,

     * not in {@link #nextElements}, this method throws an {@link UnknownElementException}.
     *
     * <p>This method is used when testing iterators without a known ordering. We poll the target
     * iterator's next element and pass it to the reference iterator through this method so it can
     * return the same element. This enables the assertion to pass and the reference iterator to

     * not in {@link #nextElements}, this method throws an {@link UnknownElementException}.
     *
     * <p>This method is used when testing iterators without a known ordering. We poll the target
     * iterator's next element and pass it to the reference iterator through this method so it can
     * return the same element. This enables the assertion to pass and the reference iterator to

        });

        Thread reader = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    statusSetLatch.countDown();
                    // Poll for status change instead of fixed sleep
                    long startTime = System.currentTimeMillis();
                    while (System.currentTimeMillis() - startTime < 500) {

            final List<Tuple3<String, String, String>> taskList = new ArrayList<>();
            while (generating) {
                try {
                    final Tuple3<String, String, String> task = thumbnailTaskQueue.poll(thumbnailTaskQueueTimeout, TimeUnit.MILLISECONDS);
                    if (task == null) {
                        if (!taskList.isEmpty()) {
                            storeQueue(taskList);
                        }

    /**
     * Creates a new fixed thread pool executor with the specified number of threads.
     *
     * @param nThreads the number of threads in the pool
     * @return a new ThreadPoolExecutor configured for this callback
     */
    protected ExecutorService newFixedThreadPool(final int nThreads) {
        if (logger.isDebugEnabled()) {
            logger.debug("Initialized executor thread pool: size={}", nThreads);
        }