void testThreadSafety() throws InterruptedException {
        SimpleCircuitBreaker breaker = new SimpleCircuitBreaker("concurrent", 5, 3, 100);
        AtomicInteger successCount = new AtomicInteger(0);
        AtomicInteger failureCount = new AtomicInteger(0);

        // Create multiple threads
        Thread[] threads = new Thread[10];
        for (int i = 0; i < threads.length; i++) {
            final int index = i;

        HALF_OPEN
    }

    private final String name;
    private final AtomicReference<State> state = new AtomicReference<>(State.CLOSED);
    private final AtomicInteger failureCount = new AtomicInteger(0);
    private final AtomicInteger successCount = new AtomicInteger(0);
    private final AtomicLong lastFailureTime = new AtomicLong(0);
    private final AtomicLong lastStateChangeTime = new AtomicLong(System.currentTimeMillis());

        final int numThreads = 10;
        final ExecutorService executor = Executors.newFixedThreadPool(numThreads);
        final CountDownLatch latch = new CountDownLatch(numThreads);
        final AtomicInteger callbackCount = new AtomicInteger(0);

        // Add listeners concurrently from multiple threads
        for (int i = 0; i < numThreads; i++) {
            executor.submit(() -> {
                try {

    while (true) {
      AtomicInteger existingCounter = safeGet(countMap, element);
      if (existingCounter == null) {
        existingCounter = countMap.putIfAbsent(element, new AtomicInteger(occurrences));
        if (existingCounter == null) {
          return 0;
        }
        // existingCounter != null: fall through to operate against the existing AtomicInteger
      }

      while (true) {

   */
  public void testAdd_withFailures() {
    AtomicInteger existing = new AtomicInteger(12);
    AtomicInteger existingZero = new AtomicInteger(0);

    // initial map.get()
    when(backingMap.get(KEY)).thenReturn(null);
    // since get returned null, try a putIfAbsent; that fails due to a simulated race
    when(backingMap.putIfAbsent(eq(KEY), isA(AtomicInteger.class))).thenReturn(existingZero);

        CountDownLatch startLatch = new CountDownLatch(1);
        CountDownLatch endLatch = new CountDownLatch(threadCount);
        AtomicInteger releaseCount = new AtomicInteger(0);
        AtomicInteger acquireCount = new AtomicInteger(0);

        // Acquire session multiple times
        for (int i = 0; i < threadCount - 1; i++) {
            session.acquire();
        }

  }

  public void testConstructingWithNullExecutor_fails() {
    assertThrows(NullPointerException.class, () -> new SequentialExecutor(null));
  }

  public void testBasics() {
    AtomicInteger totalCalls = new AtomicInteger();
    Runnable intCounter =
        new Runnable() {
          @Override
          public void run() {
            totalCalls.incrementAndGet();

   */
  public void testBuilder_bruteForce() {
    for (int i = 0; i < reduceIterationsIfGwt(100); i++) {
      ImmutableDoubleArray.Builder builder = ImmutableDoubleArray.builder(random.nextInt(20));
      AtomicInteger counter = new AtomicInteger(0);
      while (counter.get() < 1000) {
        BuilderOp op = BuilderOp.randomOp();
        op.doIt(builder, counter);
      }
      ImmutableDoubleArray iia = builder.build();

    FakeTicker ticker = new FakeTicker();
    AtomicInteger evictionCount = new AtomicInteger();
    AtomicInteger applyCount = new AtomicInteger();
    AtomicInteger totalSum = new AtomicInteger();

    RemovalListener<Integer, AtomicInteger> removalListener =
        new RemovalListener<Integer, AtomicInteger>() {
          @Override

  }

  public void testConstructingWithNullExecutor_fails() {
    assertThrows(NullPointerException.class, () -> new SequentialExecutor(null));
  }

  public void testBasics() {
    AtomicInteger totalCalls = new AtomicInteger();
    Runnable intCounter =
        new Runnable() {
          @Override
          public void run() {
            totalCalls.incrementAndGet();