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

                                    + now
                                    + ", lastUpdated = " + lastUpdated + "). Please verify that the clocks of all"
                                    + " deploying machines are reasonably synchronized.");
                    versioning.setLastUpdated(now);
                    changed = true;
                }
            }
        }

        if (changed) {

            if (totalProjects <= 1) {
                infoMain(building);
            } else {
                // display progress [i/n]
                int number;
                synchronized (this) {
                    number = ++currentVisitedProjectCount;
                }
                String progress = " [" + number + '/' + totalProjects + ']';

            if (totalProjects <= 1) {
                infoMain(building);
            } else {
                // display progress [i/n]
                int number;
                synchronized (this) {
                    number = ++currentVisitedProjectCount;
                }
                String progress = " [" + number + '/' + totalProjects + ']';

  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

  /** Returns true if the element is native. */
  public final boolean isNative() {
    return Modifier.isNative(getModifiers());
  }

  /** Returns true if the method is synchronized. */
  public final boolean isSynchronized() {
    return Modifier.isSynchronized(getModifiers());
  }

  /** Returns true if the field is volatile. */
  final boolean isVolatile() {
    return Modifier.isVolatile(getModifiers());
  }

    public int available() throws IOException {
      return (int) min(in.available(), left);
    }

    // it's okay to mark even if mark isn't supported, as reset won't work
    @Override
    public synchronized void mark(int readLimit) {
      in.mark(readLimit);
      mark = left;
    }

    @Override
    public int read() throws IOException {
      if (left == 0) {
        return -1;
      }