checkConcurrencyLevel(7, 8);
    checkConcurrencyLevel(8, 8);
  }

  private static void checkConcurrencyLevel(int concurrencyLevel, int segmentCount) {
    LocalCache<Object, Object> map =
        makeLocalCache(createCacheBuilder().concurrencyLevel(concurrencyLevel));
    assertThat(map.segments).hasLength(segmentCount);
  }

  public void testSetInitialCapacity() {

   *
   * @throws IllegalArgumentException if {@code concurrencyLevel} is nonpositive
   * @throws IllegalStateException if a concurrency level was already set
   */
  @CanIgnoreReturnValue
  public MapMaker concurrencyLevel(int concurrencyLevel) {
    checkState(
        this.concurrencyLevel == UNSET_INT,
        "concurrency level was already set to %s",
        this.concurrencyLevel);
    checkArgument(concurrencyLevel > 0);

   */
  @CanIgnoreReturnValue
  public CacheBuilder<K, V> concurrencyLevel(int concurrencyLevel) {
    checkState(
        this.concurrencyLevel == UNSET_INT,
        "concurrency level was already set to %s",
        this.concurrencyLevel);
    checkArgument(concurrencyLevel > 0);
    this.concurrencyLevel = concurrencyLevel;
    return this;
  }

  int getConcurrencyLevel() {

    assertThrows(IllegalArgumentException.class, () -> builder.concurrencyLevel(0));
  }

  public void testConcurrencyLevel_setTwice() {
    CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder().concurrencyLevel(16);
    assertThrows(IllegalStateException.class, () -> builder.concurrencyLevel(16));
  }

  @GwtIncompatible // CacheTesting
  public void testConcurrencyLevel_small() {

    assertThrows(IllegalArgumentException.class, () -> builder.concurrencyLevel(0));
  }

  public void testConcurrencyLevel_setTwice() {
    CacheBuilder<Object, Object> builder = CacheBuilder.newBuilder().concurrencyLevel(16);
    assertThrows(IllegalStateException.class, () -> builder.concurrencyLevel(16));
  }

  @GwtIncompatible // CacheTesting
  public void testConcurrencyLevel_small() {

    concurrencyLevel = min(builder.getConcurrencyLevel(), MAX_SEGMENTS);

    keyEquivalence = builder.getKeyEquivalence();
    this.entryHelper = entryHelper;

    int initialCapacity = min(builder.getInitialCapacity(), MAXIMUM_CAPACITY);

    // Find power-of-two sizes best matching arguments. Constraints:
    // (segmentCount > concurrencyLevel)
    int segmentShift = 0;

    FakeTicker ticker = new FakeTicker();
    IdentityLoader<Integer> loader = identityLoader();
    LoadingCache<Integer, Integer> cache =
        CacheBuilder.newBuilder()
            .concurrencyLevel(1)
            .expireAfterAccess(11, MILLISECONDS)
            .ticker(ticker)
            .build(loader);
    for (int i = 0; i < 10; i++) {
      cache.getUnchecked(i);
      ticker.advance(1, MILLISECONDS);

       * UnsignedBytesBenchmark. TODO(cpovirk): benchmark this
       */
      /*
       * A CopyOnWriteArraySet<WeakReference> is faster than a newSetFromMap of a MapMaker map with
       * weakKeys() and concurrencyLevel(1), even up to at least 12 cached exception types.
       */
      private static final Set<WeakReference<Class<? extends Exception>>> validClasses =
          new CopyOnWriteArraySet<>();

      @Override

       * UnsignedBytesBenchmark. TODO(cpovirk): benchmark this
       */
      /*
       * A CopyOnWriteArraySet<WeakReference> is faster than a newSetFromMap of a MapMaker map with
       * weakKeys() and concurrencyLevel(1), even up to at least 12 cached exception types.
       */
      private static final Set<WeakReference<Class<? extends Exception>>> validClasses =
          new CopyOnWriteArraySet<>();

      @Override

     * @param concurrencyLevel the estimated number of threads for concurrent updates
     * @return a new instance of {@link ConcurrentHashMap}
     * @see ConcurrentHashMap#ConcurrentHashMap(int, float, int)
     */
    public static <K, V> ConcurrentHashMap<K, V> newConcurrentHashMap(final int initialCapacity, final float loadFactor,
            final int concurrencyLevel) {