*
     * Our solution is for threads to CAS seenExceptions from null to a Set populated with _the
     * initial exception_, no matter which thread does the work. This ensures that seenExceptions
     * always contains not just the current thread's exception but also the initial thread's.
     */
    Set<Throwable> seenExceptionsLocal = seenExceptions;

    for (int i = 0; i < numThreads; i++) {
      threads[i] =
          new Thread() {
            @Override
            public void run() {
              assertSame(Boolean.TRUE, memoizedSupplier.get());
            }
          };
    }
    for (Thread t : threads) {
      t.start();
    }
    for (Thread t : threads) {
      t.join();
    }

    if (thrown.get() != null) {

    for (int i = 0; i < numThreads; i++) {
      threads[i] =
          new Thread() {
            @Override
            public void run() {
              assertSame(Boolean.TRUE, memoizedSupplier.get());
            }
          };
    }
    for (Thread t : threads) {
      t.start();
    }
    for (Thread t : threads) {
      t.join();
    }

    if (thrown.get() != null) {

   *       directExecutor}, the listener can execute in any of three possible threads:
   *       <ol>
   *         <li>When a thread attaches a listener to a {@code ListenableFuture} that's already
   *             complete, the listener runs immediately in that thread.
   *         <li>When a thread attaches a listener to a {@code ListenableFuture} that's

    start();
  }

  // Thread.stop() is okay because all threads started by a test are dying at the end of the test,
  // so there is no object state put at risk by stopping the threads abruptly. In some cases a test
  // may put a thread into an uninterruptible operation intentionally, so there is no other way to
  // clean up these threads.
  @SuppressWarnings("deprecation")
  @Override

   * there would exist a perfect hash function mapping threads to
   * slots that eliminates collisions. When we reach capacity, we
   * search for this mapping by randomly varying the hash codes of
   * colliding threads.  Because search is random, and collisions
   * only become known via CAS failures, convergence can be slow,
   * and because threads are typically not bound to CPUS forever,
   * may not occur at all. However, despite these limitations,

            });
    assertFalse(task.isDone());
    Thread thread =
        new Thread(
            new Runnable() {
              @Override
              public void run() {
                try {
                  task.run();
                } finally {
                  exitLatch.countDown();
                }
              }
            });
    thread.start();
    enterLatch.await();

    assertFalse(future.isDone());
    assertFalse(future.isCancelled());

    CountDownLatch successLatch = new CountDownLatch(1);

    // Run cancellation in a separate thread as an extra thread-safety test.
    new Thread(
            () -> {
              assertThrows(CancellationException.class, future::get);
              successLatch.countDown();
            })
        .start();

          @Override
          public void run() {
            list.execute();
          }
        };
    Thread thread1 = new Thread(execute);
    Thread thread2 = new Thread(execute);
    thread1.start();
    thread2.start();
    assertEquals(0, runCalled.get());
    okayToRun.countDown();
    thread1.join();
    thread2.join();
    assertEquals(1, runCalled.get());
  }

  public void testAddAfterRun() throws Exception {

            }
          }
        });
    awaitUninterruptibly(enteredLatch);
  }

  @CanIgnoreReturnValue
  static Thread startThread(Runnable runnable) {
    Thread thread = new Thread(runnable);
    thread.setDaemon(true);
    thread.start();
    return thread;
  }

  /**
   * Generates a test case verifying that calling any enterXxx, tryEnterXxx, or waitForXxx method