}

  private static class TestApplication extends Application {
    private final List<Thread> hooks = new ArrayList<>();

    @Override
    synchronized void addShutdownHook(Thread hook) {
      hooks.add(hook);
    }

    synchronized void shutdown() throws InterruptedException {
      for (Thread hook : hooks) {
        hook.start();
      }
      for (Thread hook : hooks) {
        hook.join();

            }
        }

        artifactRepositories = repositorySystem.getEffectiveRepositories(artifactRepositories);

        return artifactRepositories;
    }

    @Override
    public synchronized ProjectRealmCache.CacheRecord createProjectRealm(
            MavenProject project, Model model, ProjectBuildingRequest request)

                            synchronized (project) {
                                cleanProjectLocalRepository(project);
                            }
                        }
                    }
                }
                break;
            case ProjectSucceeded:
            case ForkedProjectSucceeded:
                synchronized (project) {

    }
  }

  private static final class TimeoutFutureException extends TimeoutException {
    private TimeoutFutureException(String message) {
      super(message);
    }

    @Override
    public synchronized Throwable fillInStackTrace() {
      setStackTrace(new StackTraceElement[0]);
      return this; // no stack trace, wouldn't be useful anyway
    }
  }

  @Override

        ProjectArtifactsCache.CacheRecord recordArtifacts;
        recordArtifacts = projectArtifactsCache.get(cacheKey);
        if (recordArtifacts == null) {
            synchronized (cacheKey) {
                recordArtifacts = projectArtifactsCache.get(cacheKey);
                if (recordArtifacts == null) {
                    try {

        .suppressing(suppressForEnumSet())
        .createTestSuite();
  }

  /**
   * Tests regular NavigableSet behavior of synchronizedNavigableSet(treeSet); does not test the
   * fact that it's synchronized.
   */
  public Test testsForSynchronizedNavigableSet() {
    return NavigableSetTestSuiteBuilder.using(
            new TestStringSortedSetGenerator() {
              @Override

  private class RecordingPushObserver :
    PushObserver,
    Lockable {
    val events = mutableListOf<Any>()

    @Synchronized fun takeEvent(): Any {
      while (events.isEmpty()) {
        wait()
      }
      return events.removeAt(0)
    }

    @Synchronized override fun onRequest(
      streamId: Int,
      requestHeaders: List<Header>,
    ): Boolean {

As the execution time is consumed mostly by waiting for <abbr title="Input and Output">I/O</abbr> operations, they call them "I/O bound" operations.

It's called "asynchronous" because the computer / program doesn't have to be "synchronized" with the slow task, waiting for the exact moment that the task finishes, while doing nothing, to be able to take the task result and continue the work.

    public org.apache.maven.api.plugin.descriptor.PluginDescriptor getPluginDescriptorV4() {
        if (pluginDescriptorV4 == null) {
            synchronized (this) {
                if (pluginDescriptorV4 == null) {
                    pluginDescriptorV4 = org.apache.maven.api.plugin.descriptor.PluginDescriptor.newBuilder()
                            .namespaceUri(null)

  public void testOrderingUnmodifiable() {
    SetMultimap<String, Integer> multimap = initializeMultimap5();
    assertOrderingReadOnly(Multimaps.unmodifiableMultimap(multimap));
  }

  @J2ktIncompatible // Synchronized
  public void testOrderingSynchronized() {
    SetMultimap<String, Integer> multimap = initializeMultimap5();
    assertOrderingReadOnly(synchronizedMultimap(multimap));
  }

  @J2ktIncompatible