线程守卫

此类仅在Java中可用

ThreadGuard检查是否仅从创建驱动程序的同一线程中调用了驱动程序. 线程问题 (尤其是在Parallel中运行测试时) 可能遇到神秘并且难以诊断错误. 使用此包装器可以防止此类错误,
并且在发生此类情况时会抛出异常.

以下的示例模拟一种线程冲突的情况:

public class DriverClash {
  //thread main (id 1) created this driver
  private WebDriver protectedDriver = ThreadGuard.protect(new ChromeDriver());

  static {
    System.setProperty("webdriver.chrome.driver", "<Set path to your Chromedriver>");
  }

  //Thread-1 (id 24) is calling the same driver causing the clash to happen
  Runnable r1 = () -> {protectedDriver.get("https://selenium.dev");};
  Thread thr1 = new Thread(r1);

  void runThreads(){
    thr1.start();
  }

  public static void main(String[] args) {
    new DriverClash().runThreads();
  }
}

结果如下所示:

Exception in thread "Thread-1" org.openqa.selenium.WebDriverException:
Thread safety error; this instance of WebDriver was constructed
on thread main (id 1)and is being accessed by thread Thread-1 (id 24)
This is not permitted and *will* cause undefined behaviour

正如示例所示:

  • protectedDriver 将在主线程中创建
  • 我们使用Java的 Runnable 启动一个新进程, 并使用一个新的 Thread 运行该进程
  • 这两个 Thread 都会发生冲突, 因为主线程的内存中没有 protectedDriver
  • ThreadGuard.protect 会抛出异常

注意:

这不能代替并发运行时使用 ThreadLocal 管理驱动程序的需求.