WebBrowser已经使用了Window Manager对象的所有系统允许句柄

Question

我正在编写一个Web爬虫，它使用WebBrowser在网页中呈现javascript，然后吐出html代码进行抓取。我遇到的问题是，看起来打开的虚拟浏览器窗口没有关闭，因为在几分钟的爬行后我收到此错误：未处理的异常：System.Runtime.InteropServices.COMException：当前进程已使用其所有系统允许的窗口管理器对象的句柄 我在MVC Web项目中编写此代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Threading;

namespace Abot.Demo
{
    // Threaded version
    public class HeadlessBrowser
    {
        private static string GeneratedSource { get; set; }
        private static string URL { get; set; }

        public static string GetGeneratedHTML(string url)
        {
            string result = null;
            ThreadStart pumpMessages = () =>
            {
                EventHandler idleHandler = null;
                idleHandler = (s, e) =>
                {
                    Application.Idle -= idleHandler;

                    WebBrowser wb = new WebBrowser();
                    wb.DocumentCompleted += (s2, e2) =>
                    {
                        result = wb.Document.Body.InnerHtml;
                        wb.Dispose();
                        Application.Exit();
                    };
                    try
                    {
                        wb.Navigate(url);
                    }
                    catch(Exception ex)
                    {
                        Console.WriteLine(ex.ToString());
                    }

                };
                Application.Idle += idleHandler;
                Application.Run();
            };
            if (Thread.CurrentThread.GetApartmentState() == ApartmentState.STA)
                pumpMessages();
            else
            {
                Thread t = new Thread(pumpMessages);
                t.SetApartmentState(ApartmentState.STA);
                t.Start();
                t.Join();
            }
            return result;
        }

        private static void WebBrowserThread()
        {
            WebBrowser wb = new WebBrowser();
            try
            {
                wb.Navigate(URL);
            }
            catch(Exception exc)
            {
                Console.WriteLine(exc);
            }
            wb.DocumentCompleted +=
                new WebBrowserDocumentCompletedEventHandler(
                    wb_DocumentCompleted);

            while (wb.ReadyState != WebBrowserReadyState.Complete);

            //Added this line, because the final HTML takes a while to show up
            GeneratedSource = wb.Document.Body.InnerHtml;

            wb.Dispose();
            wb.Stop();
        }



        private static void wb_DocumentCompleted(object sender,
            WebBrowserDocumentCompletedEventArgs e)
        {
            WebBrowser wb = (WebBrowser)sender;
            GeneratedSource = wb.Document.Body.InnerHtml;
        }

    }
}