SendAsync 正在阻塞 UI 个线程

Question

正在尝试将我的部分程序转换为异步 http 客户端调用。取出部分代码（如下）进行测试。基本上是一个非阻塞的异步按钮（据我所知）SendAsync()。它不应该阻塞 UI 线程，我说得对吗？由于我目前看不到的原因，它仍然阻止它。

过去 2 天我一直在努力找出问题所在。我实现了非阻塞文件写入日志记录和电子邮件发送功能，它们工作正常。

有人能指出我做错了什么吗？

private async void button2_Click(object sender, EventArgs e)
    {
    NetworkCredential differentCredToPass = new NetworkCredential("user", "*****", "domain");
    WebProxy wcProxy = new WebProxy("1.1.1.1", 8080);
    wcProxy.UseDefaultCredentials = false;
    wcProxy.Credentials = differentCredToPass;
    var httpHandler = new HttpClientHandler();
    httpHandler.UseProxy = true;
    httpHandler.UseDefaultCredentials = false;
    httpHandler.Proxy = wcProxy;
    using(HttpClient httpClient = new HttpClient(httpHandler) )
        {
        try
            {
            HttpRequestMessage request = new HttpRequestMessage(HttpMethod.Get, "http://cisco.Com");
            HttpResponseMessage response = await httpClient.SendAsync(request);
            textBox1.AppendText(response.StatusCode.ToString() + Environment.NewLine);
            }
        catch (Exception ex)
            {
            textBox1.AppendText(ex.Message.ToString() + Environment.NewLine);
            throw;
            }
        }
    }

Answer 1

non-blocking (should be to my knowledge) SendAsync()

好吧，是的，也不是。不幸的是，由于历史原因，SendAsync 并不是 纯粹的 异步。具体来说，它同步进行 DNS 查找和代理解析。因此，要使其完全非阻塞，您需要将该调用包装在 Task.Run:

HttpResponseMessage response = await Task.Run(() => httpClient.SendAsync(request));

SendAsync 正在阻塞 UI 个线程

SendAsync is blocking UI thread

c#

http

asynchronous

sendasync