code: // Licensed to the Software Freedom Conservancy (SFC) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The SFC licenses this file
  // to you under the Apache License, Version 2.0 (the
  // "License"); you may not use this file except in compliance
  // with the License.  You may obtain a copy of the License at
  //
  //   http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing,
  // software distributed under the License is distributed on an
  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, either express or implied.  See the License for the
  // specific language governing permissions and limitations
  // under the License.
  
  package org.openqa.selenium.grid.router;
  
  import static java.nio.charset.StandardCharsets.UTF_8;
  import static java.util.concurrent.TimeUnit.MINUTES;
  import static org.assertj.core.api.Assertions.assertThat;
  
  import java.io.StringReader;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.concurrent.CompletableFuture;
  import java.util.concurrent.ExecutorService;
  import java.util.concurrent.Executors;
  import org.junit.jupiter.api.AfterEach;
  import org.junit.jupiter.api.BeforeEach;
  import org.junit.jupiter.api.Test;
  import org.openqa.selenium.By;
  import org.openqa.selenium.WebDriver;
  import org.openqa.selenium.grid.config.MapConfig;
  import org.openqa.selenium.grid.config.MemoizedConfig;
  import org.openqa.selenium.grid.config.TomlConfig;
  import org.openqa.selenium.grid.router.DeploymentTypes.Deployment;
  import org.openqa.selenium.grid.server.BaseServerOptions;
  import org.openqa.selenium.grid.server.Server;
  import org.openqa.selenium.netty.server.NettyServer;
  import org.openqa.selenium.remote.RemoteWebDriver;
  import org.openqa.selenium.remote.http.Contents;
  import org.openqa.selenium.remote.http.HttpResponse;
  import org.openqa.selenium.testing.Safely;
  import org.openqa.selenium.testing.TearDownFixture;
  import org.openqa.selenium.testing.drivers.Browser;
  
  class StressTest {
  
    private final ExecutorService executor =
        Executors.newFixedThreadPool(Runtime.getRuntime().availableProcessors() * 2);
    private final List<TearDownFixture> tearDowns = new LinkedList<>();
    private Server<?> server;
    private Browser browser;
    private Server<?> appServer;
  
    @BeforeEach
    public void setupServers() {
      browser = Objects.requireNonNull(Browser.detect());
  
      Deployment deployment =
          DeploymentTypes.DISTRIBUTED.start(
              browser.getCapabilities(),
              new TomlConfig(
                  new StringReader(
                      "[node]\n"
                          + "selenium-manager = true\n"
                          + "driver-implementation = "
                          + browser.displayName())));
      tearDowns.add(deployment);
  
      server = deployment.getServer();
  
      appServer =
          new NettyServer(
              new BaseServerOptions(new MemoizedConfig(new MapConfig(Map.of()))),
              req -> {
                try {
                  Thread.sleep(2000);
                } catch (InterruptedException e) {
                  throw new RuntimeException(e);
                }
                return new HttpResponse().setContent(Contents.string("<h1>Cheese</h1>", UTF_8));
              });
  
      tearDowns.add(() -> appServer.stop());
      appServer.start();
    }
  
    @AfterEach
    public void tearDown() {
      tearDowns.parallelStream().forEach(Safely::safelyCall);
      executor.shutdownNow();
    }
  
    @Test
    void multipleSimultaneousSessions() throws Exception {
      assertThat(server.isStarted()).isTrue();
  
      CompletableFuture<?>[] futures = new CompletableFuture<?>[10];
      for (int i = 0; i < futures.length; i++) {
        CompletableFuture<Object> future = new CompletableFuture<>();
        futures[i] = future;
  
        executor.submit(
            () -> {
              try {
                WebDriver driver =
                    RemoteWebDriver.builder()
                        .oneOf(browser.getCapabilities())
                        .address(server.getUrl())
                        .build();
  
                driver.get(appServer.getUrl().toString());
                driver.findElement(By.tagName("body"));
  
                // And now quit
                driver.quit();
                future.complete(true);
              } catch (Exception e) {
                future.completeExceptionally(e);
              }
            });
      }
  
      CompletableFuture.allOf(futures).get(4, MINUTES);
    }
  }
  