otherThread.start();
        latch.await();

        // Verify other thread had different values
        assertEquals("other-thread", otherThreadUrlQueueSessionId.get());
        assertEquals("other-context", otherThreadContextSessionId.get());

        // Verify main thread values are unchanged
        assertEquals("main-thread", CrawlingParameterUtil.getUrlQueue().getSessionId());

    }
  }

  /** Confirm all tasks have completed. Used by the test thread only. */
  fun assertNoMoreTasks() {
    taskRunner.assertLockNotHeld()

    taskRunner.withLock {
      assertThat(activeThreads).isEqualTo(0)
    }
  }

  /** Unblock a waiting task thread. Used by the test thread only. */
  fun interruptCoordinatorThread() {
    taskRunner.assertLockNotHeld()

        try (MappingUpdater updater = new MappingUpdater(item)) {
            reload(updater);
        }
    }

    /**
     * Reloads the character mapping items from the dictionary file.
     *
     * @param updater the mapping updater to use for writing changes, or null for read-only reload
     */
    protected void reload(final MappingUpdater updater) {

        // Trip circuit
        circuitBreaker.trip();
        Thread.sleep(100);

        long afterTripTime = circuitBreaker.getTimeSinceLastStateChange();
        assertTrue(afterTripTime >= 100, "Time should have advanced");
        assertTrue(afterTripTime < 200, "Time should be reasonable");

        // Reset circuit
        circuitBreaker.reset();
        Thread.sleep(50);

    }
  }

  /** Wait for the given thread to reach the {@link State#TIMED_WAITING} thread state. */
  @SuppressWarnings("ThreadPriorityCheck") // TODO: b/175898629 - Consider onSpinWait.
  void awaitTimedWaiting(Thread thread) {
    while (true) {
      switch (thread.getState()) {
        case BLOCKED:
        case NEW:
        case RUNNABLE:
        case WAITING:
          Thread.yield();
          break;

  protected AbstractExecutionThreadService() {}

  /**
   * Start the service. This method is invoked on the execution thread.
   *
   * <p>By default this method does nothing.
   */
  protected void startUp() throws Exception {}

  /**
   * Run the service. This method is invoked on the execution thread. Implementations must respond
   * to stop requests. You could poll for lifecycle changes in a work loop:
   *
   * <pre>

  }
}

internal inline fun Lockable.assertLockNotHeld() {
  if (assertionsEnabled && Thread.holdsLock(this)) {
    throw AssertionError("Thread ${Thread.currentThread().name} MUST NOT hold lock on $this")
  }
}

internal inline fun Lockable.assertLockHeld() {
  if (assertionsEnabled && !Thread.holdsLock(this)) {
    throw AssertionError("Thread ${Thread.currentThread().name} MUST hold lock on $this")
  }
}

                }
            });
            readThreads[i].start();
        }

        // Wait for all threads
        for (Thread thread : updateThreads) {
            thread.join(5000);
        }
        for (Thread thread : readThreads) {
            thread.join(5000);
        }

        // Verify final state
        assertEquals(100, entry.getChildren().size());

 */
public class SystemProperties {
    /**
     * Thread-safe System.properties copy implementation.
     */
    public static void addSystemProperties(Properties props) {
        props.putAll(getSystemProperties());
    }

    /**
     * Returns a copy of {@link System#getProperties()} in a thread-safe manner.
     *
     * @return {@link System#getProperties()} obtained in a thread-safe manner.
     */

      return;
    }
    TimedWaiterThread thread = new TimedWaiterThread(new AbstractFuture<Object>() {}, 2, SECONDS);
    thread.start();
    thread.awaitWaiting();
    Thread.class.getMethod("suspend").invoke(thread);
    // Sleep for enough time to add 1500 milliseconds of overwait to the get() call.
    long toWaitMillis = 3500 - NANOSECONDS.toMillis(System.nanoTime() - thread.startTime);
    Thread.sleep(toWaitMillis);