/**
   * When we need a new thread to run tasks, we call [Backend.execute]. A few microseconds later we
   * expect a newly-started thread to call [Runnable.run]. We shouldn't request new threads until
   * the already-requested ones are in service, otherwise we might create more threads than we need.
   *
   * We use [executeCallCount] and [runCallCount] to defend against starting more threads than we

#### Shared reader thread

            });
        }

        for (Thread th : threads) {
            th.start();
        }
        for (Thread th : threads) {
            th.join();
        }
        assertEquals(num, count.get());
        assertEquals(num, valueSet.size());

        Set<String> valueSet2 = Collections.synchronizedSet(new HashSet<>());
        threads = new Thread[threadNum];

            });
    assertFalse(task.isDone());
    Thread thread =
        new Thread(
            () -> {
              try {
                task.run();
              } finally {
                exitLatch.countDown();
              }
            },
            "Custom thread name");
    thread.start();
    enterLatch.await();
    assertFalse(task.isDone());

        directExecutor());
    service.startAsync().awaitRunning();

    Thread thread =
        new Thread() {
          @Override
          public void run() {
            service.stopAsync().awaitTerminated();
          }
        };
    thread.start();
    thread.join(LONG_TIMEOUT_MILLIS);
    assertFalse(thread + " is deadlocked", thread.isAlive());
  }

        directExecutor());
    service.startAsync().awaitRunning();

    Thread thread =
        new Thread() {
          @Override
          public void run() {
            service.stopAsync().awaitTerminated();
          }
        };
    thread.start();
    thread.join(LONG_TIMEOUT_MILLIS);
    assertFalse(thread + " is deadlocked", thread.isAlive());
  }

 * thread) the subscriber is actually called when an event is dispatched to it.
 *
 * @author Colin Decker
 */
abstract class Dispatcher {

  /**
   * Returns a dispatcher that queues events that are posted reentrantly on a thread that is already
   * dispatching an event, guaranteeing that all events posted on a single thread are dispatched to

     *
     * 1. The client thread begins to block on a get() call to a future.
     * 2. The client thread is interrupted sometime before the result would be
     *   available.
     * 3. We expect the client's get() to throw an InterruptedException.
     * 4. We expect the client thread's interrupt state to be false.
     * 5. The client thread again makes a blocking call to get().

      }
      return;
    }

    /*
     * This is an unsynchronized read! After the read, the function returns immediately or acquires
     * the lock to check again. Since an IDLE state was observed inside the preceding synchronized
     * block, and reference field assignment is atomic, this may save reacquiring the lock when
     * another thread or the worker task has cleared the count and set the state.
     *

  /** Returns a new started daemon Thread running the given runnable. */
  final Thread newStartedThread(Runnable runnable) {
    Thread t = new Thread(runnable);
    t.setDaemon(true);
    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