.heldCertificate(localhostCertificate)
        .build();
    MockWebServer server = new MockWebServer();
    server.useHttps(serverCertificates.sslSocketFactory(), false);
    server.enqueue(new MockResponse());

    HandshakeCertificates clientCertificates = new HandshakeCertificates.Builder()
        .addTrustedCertificate(localhostCertificate.certificate())
        .build();

    /** Available send credits for flow control */
    protected final AtomicInteger sendCredits;
    /** Available receive credits for flow control */
    protected final AtomicInteger receiveCredits;
    /** Queue of pending RDMA work requests */
    protected final BlockingQueue<RdmaWorkRequest> pendingRequests;

    // Connection state
    /** Current connection state */
    protected volatile RdmaConnectionState state;

  Callback {
  private var call: Call? = null

  @Volatile private var canceled = false

  fun connect(callFactory: Call.Factory) {
    call =
      callFactory.newCall(request).apply {
        enqueue(this@RealEventSource)
      }
  }

  override fun onResponse(
    call: Call,
    response: Response,
  ) {
    processResponse(response)
  }

  fun processResponse(response: Response) {

    OkHttpCaller.callOkHttp(HttpUrl.get("https://square.com/robots.txt"));
  }

  @Test
  public void testMockWebServer() throws IOException {
    MockWebServer server = new MockWebServer();
    server.enqueue(new MockResponse(200, Headers.of(), "Hello, Java9!"));
    server.start();

    // Just check we can run code that depends on OkHttp types
    Call call = OkHttpCaller.callOkHttp(server.url("/"));

  @StartStop
  private val server = MockWebServer()

  @BeforeEach fun setUp() {
    client.start()
  }

  @AfterEach fun tearDown() {
    client.stop()
  }

  @Test fun get() {
    server.enqueue(MockResponse(body = "hello, Jetty HTTP Client"))

    val request =
      client
        .newRequest(server.url("/").toUri())
        .header("Accept", "text/plain")
    val response = request.send()

  private val client = OkHttpClient()

  fun run() {
    val request =
      Request
        .Builder()
        .url("http://publicobject.com/helloworld.txt")
        .build()

    client.newCall(request).enqueue(
      object : Callback {
        override fun onFailure(
          call: Call,
          e: IOException,
        ) {
          e.printStackTrace()
        }

        override fun onResponse(

				_ = syscall.SetsockoptInt(fd, syscall.IPPROTO_TCP, unix.TCP_NODELAY, 1)
				_ = syscall.SetsockoptInt(fd, syscall.SOL_TCP, unix.TCP_CORK, 0)
			}

			// Enable TCP open
			// https://lwn.net/Articles/508865/ - 32k queue size.
			_ = syscall.SetsockoptInt(fd, syscall.SOL_TCP, unix.TCP_FASTOPEN, 32*1024)

			// Enable TCP fast connect
			// TCPFastOpenConnect sets the underlying socket to use

import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Locale;
import java.util.Map;
import java.util.NavigableMap;
import java.util.NavigableSet;
import java.util.Queue;
import java.util.Random;
import java.util.Set;
import java.util.SortedMap;
import java.util.SortedSet;
import java.util.UUID;
import java.util.concurrent.BlockingDeque;

        }
    }

    /**
     * Stores a failure URL with error information for later analysis.
     *
     * @param crawlerContext the crawler context
     * @param urlQueue the URL queue containing the failed URL
     * @param errorName the name/type of the error
     * @param e the throwable that caused the failure
     * @return the stored FailureUrl entity
     */

They tend to require more complex configurations, a message/job queue manager, like RabbitMQ or Redis, but they allow you to run background tasks in multiple processes, and especially, in multiple servers.