private final Executor executor;

    public DefaultArtifactResolver() {
        int threads = Integer.getInteger("maven.artifact.threads", 5);
        if (threads <= 1) {
            executor = Runnable::run;
        } else {
            executor = new ThreadPoolExecutor(
                    threads, threads, 3, TimeUnit.SECONDS, new LinkedBlockingQueue<>(), new DaemonThreadCreator());
        }
    }

 * under the License.
 */

/**
 * Provides an immutable XML processing API for Maven, offering classes and interfaces
 * for reading, manipulating, and writing XML documents in a thread-safe manner.
 * This package is used extensively for POM, settings, and other Maven configuration files.
 *
 * @since 4.0.0
 */

 *   <li>Handle project forking states</li>
 * </ul>
 *
 * The service maintains the mutable state of projects as they progress through
 * their build lifecycle, ensuring thread-safety and proper state management.
 * All implementations must be thread-safe as they may be accessed concurrently
 * during parallel builds.
 *
 * @since 4.0.0
 * @see org.apache.maven.api.services.ProjectBuilder
 * @see Project
 */
@Experimental

          protected void doStart() {
            new Thread() {
              @Override
              public void run() {
                notifyStarted();
                // We need to wait for the main thread to leave the ServiceManager.startAsync call
                // to
                // ensure that the thread running the failure callbacks is not the main thread.
                Uninterruptibles.awaitUninterruptibly(afterStarted);

          /* Someone beat us to it! Trying again...
           *
           * Technically this loop not guaranteed to terminate, so theoretically (extremely
           * unlikely) this thread might starve, but even then, there is always going to be another
           * thread doing progress here.
           */
        }
      }
    }
  }

  /**

 * <p>
 * This builder uses a number of threads equal to the minimum of the degree of concurrency (which is the thread count
 * set with <code>-T</code> on the command-line) and the number of projects to build. As such, building a single project
 * will always result in a sequential build, regardless of the thread count.
 * </p>

    void recordHits(int count);

    /**
     * Records cache misses. This should be called when a cache request returns a value that was not
     * found in the cache. This method should be called by the loading thread, as well as by threads
     * blocking on the load. Multiple concurrent calls to {@link Cache} lookup methods with the same
     * key on an absent value should result in a single call to either {@code recordLoadSuccess} or

 */
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.
     */

 * example involving two locks and two threads, deadlock occurs when one thread acquires Lock A, and
 * then Lock B, while another thread acquires Lock B, and then Lock A:
 *
 * <pre>
 * Thread1: acquire(LockA) --X acquire(LockB)
 * Thread2: acquire(LockB) --X acquire(LockA)
 * </pre>
 *
 * <p>Neither thread will progress because each is waiting for the other. In more complex

  private final CountDownLatch exitRun = new CountDownLatch(1);

  private Thread executionThread;
  private Throwable thrownByExecutionThread;
  private final Executor exceptionCatchingExecutor =
      new Executor() {
        @Override
        public void execute(Runnable command) {
          executionThread = new Thread(command);
          executionThread.setUncaughtExceptionHandler(