t.start();
    return t;
  }

  /**
   * Waits for the specified time (in milliseconds) for the thread to terminate (using {@link
   * Thread#join(long)}), else interrupts the thread (in the hope that it may terminate later) and
   * fails.
   */
  void awaitTermination(Thread t, long timeoutMillis) {
    try {
      t.join(timeoutMillis);
    } catch (InterruptedException ie) {

              @Override
              protected void finalize() {
                finalizerRan.countDown();
              }
            });

    await(finalizerRan);
    awaitClear(ref);

    // Hope to catch some stragglers queued up behind our finalizable object
    System.runFinalization();
  }

  private static RuntimeException formatRuntimeException(String format, Object... args) {

    t.start();
    return t;
  }

  /**
   * Waits for the specified time (in milliseconds) for the thread to terminate (using {@link
   * Thread#join(long)}), else interrupts the thread (in the hope that it may terminate later) and
   * fails.
   */
  void awaitTermination(Thread t, long timeoutMillis) {
    try {
      t.join(timeoutMillis);
    } catch (InterruptedException ie) {

    unfiltered.put("cat", 3);
    unfiltered.put("dog", 2);
    unfiltered.put("horse", 5);
    Map<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);
    assertEquals(ImmutableMap.of("cat", 3, "horse", 5), filtered);

    filtered.put("chicken", 7);
    assertEquals(ImmutableMap.of("cat", 3, "horse", 5, "chicken", 7), filtered);

    try {
      filtered.put("cow", 7);
      fail();

    unfiltered.put("cat", 3);
    unfiltered.put("dog", 2);
    unfiltered.put("horse", 5);
    Map<String, Integer> filtered = Maps.filterEntries(unfiltered, CORRECT_LENGTH);
    assertEquals(ImmutableMap.of("cat", 3, "horse", 5), filtered);

    filtered.put("chicken", 7);
    assertEquals(ImmutableMap.of("cat", 3, "horse", 5, "chicken", 7), filtered);

    try {
      filtered.put("cow", 7);
      fail();

              @Override
              protected void finalize() {
                finalizerRan.countDown();
              }
            });

    await(finalizerRan);
    awaitClear(ref);

    // Hope to catch some stragglers queued up behind our finalizable object
    System.runFinalization();
  }

  private static RuntimeException formatRuntimeException(String format, Object... args) {

         * large that doing the lookup is noticeably slower than redoing the work would be.
         *
         * Ideally we'd have a real eviction policy, but until we see a problem in practice, I hope
         * that this will suffice. I have not even benchmarked with different size limits.
         */
        if (validClasses.size() > 1000) {
          validClasses.clear();
        }