SendAsync正在阻塞UI线程

Question

试图将我的部分程序转换为异步http客户端调用。取出部分代码(如下所示)进行测试。基本上是一个非阻塞的异步按钮(据我所知) SendAsync()。它不应该阻止UI线程，我是正确的吗？它仍然阻止它的原因，我目前无法看到。

我花了两天时间想弄清楚到底出了什么问题。我实现了非阻塞文件，写日志和电子邮件发送功能，他们正确地工作。

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

非阻塞(据我所知) SendAsync()

好吧，是和不是。不幸的是，由于历史原因，SendAsync并不是纯异步的。具体来说，它同步执行DNS查找和代理解析。因此，要使这个完全非阻塞，您需要将该调用包装在一个Task.Run中。

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