Async/await，任务并行对于复杂的过程 运行在调试时 FINE 开启但未能 运行 没有

Question

我正在尝试与 TPL For 并行执行一个非常复杂的操作。它有 API 调用 async/await 和 selenium webdriver。

当我调试应用程序时，它 运行 很顺利，但是当我 运行 它没有调试器时，它很快就会崩溃并显示以下消息。

{System.OutOfMemoryException: Out of memory.
   at System.Drawing.Bitmap.Clone(Rectangle rect, PixelFormat format)
   at Browser_Automation.Parser.CropImage(Bitmap source, Rectangle section) in E:\Work\XXXXX\XXXXX\XXXXX Automation\JSON\SuiteParser.cs:line 598
   at XXXXX.Parser.GetCaptchaById(IWebDriver driver, String id) in E:\Work\XXXXX\XXXXX\XXXXXAutomation\JSON\SuiteParser.cs:line 577
   at Browser_Automation.Parser.<GetFirstCaptchaUrl>d__23.MoveNext() in E:\Work\XXXXX\XXXXX\XXXXXAutomation\JSON\SuiteParser.cs:line 526
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter`1.GetResult()
   at Browser_Automation.Parser.<_Execute>d__27.MoveNext() in E:\Work\SupportKing\VisaBot\Browser Automation\JSON\SuiteParser.cs:line 646}

这是代码，它指示位图内存不足....

private string GetCaptchaById(IWebDriver driver, string id)
    {
        //Getting the image, which is in this case has a url as source.
        var captcha_image = driver.FindElement(By.Id(id));
        string resultBase64 = "";
        if (captcha_image != null)
        {

            try
            {
                //Deleting previous screenshot images from the folder
                System.IO.DirectoryInfo di = new DirectoryInfo(App.Directory.FullName + "\ScreenshotImages");
                foreach (FileInfo file in di.GetFiles())
                {
                    file.Delete();
                }
            }
            catch (Exception ex)
            {
            }


            var path1 = App.Directory.FullName + "\ScreenshotImages\" + Guid.NewGuid().ToString() + ".png";

            //Creating screenshot of the full web page and saving it to the path
            ITakesScreenshot ssdriver = driver as ITakesScreenshot;
            Screenshot screenshot = ssdriver.GetScreenshot();
            Screenshot tempImage = screenshot;
            tempImage.SaveAsFile(path1, ScreenshotImageFormat.Png);

            //Creating a rectangle of same size as the captcha
            Point point = captcha_image.Location;
            point.X = point.X;
            point.Y = point.Y;
            int width = captcha_image.Size.Width;
            int height = captcha_image.Size.Height;
            Rectangle section = new Rectangle(point, new System.Drawing.Size(width, height));

            //Loding the full page image from the path
            Bitmap fullImg = new Bitmap(path1);

            //creating a new image as the same width height of the captcha
            Bitmap source = new System.Drawing.Bitmap(width, height);

            //This is the final captcha image. We are croping the captcha image from the full image with location(X,Y) and size(W,H)
            Bitmap final_image = CropImage(fullImg, section);

           resultBase64 = ConvertBitmapToBase64(final_image);
            //final_image.Save(@"E:\out.jpg");
        }

        return resultBase64;
    }

这是捕获错误的行：

Screenshot screenshot = ssdriver.GetScreenshot();

Answer 1

这里有一些事情：

1. 不要将 Parallel.For 与 async 和 await 混合使用。它不适合使用异步和等待模式。
2. 您的异常肯定是由 运行 GDI 内存不足引起的，因为您没有处理所有 Bitmaps。

System.OutOfMemoryException: Out of memory. at System.Drawing.Bitmap.Clone(Rectangle rect, PixelFormat format)

将所有位图放入 using statement。

或者在您处理完它们后立即致电 Dispose。