Question

它运行良好，但是我在api中进行了一些更改，没有添加更多的控制器，然后它停止工作，并始终抛出异常：GetAsync（）行中的“ TaskCanceledException：任务已取消” ）。结果。我增加了超时时间并无限地保持加载状态。向控制器API发出请求的代码控制器APP：

  public ActionResult Login(LoginM us)
    {
        try
        {
            cuentaM account = new cuentaM();
            HttpClient client = new HttpClient();

            var result = client.GetAsync("http://localhost:26723/api/Login" + "?email=" + us.email + "&password=" + us.password).Result;
            if (result.IsSuccessStatusCode)
            {
                account = result.Content.ReadAsAsync<cuentaM>().Result;
            }

            Session["cuenta"] = account;
            return RedirectToAction("Index", "Home");
        }
        catch (Exception ex)
        {
            throw;

        }
    }

控制器API代码：

 public HttpResponseMessage Get(string email, string password)
    {
        try
        {
            using (elevationbEntities db = new elevationbEntities())
            {
                usuario user = db.usuarios.Where(m => m.email == email && m.password == password).SingleOrDefault();
                cuentaM account = new cuentaM();
                if (user != null)
                {
                    account = (from o in db.cuentas
                               join cu in db.cuentausuarios on o.idCuenta equals cu.idCuenta
                               join u in db.usuarios on cu.idUsuario equals u.idUsuario
                               where u.idUsuario == user.idUsuario
                               select new cuentaM {  idUsuario = user.idUsuario, idCuenta = o.idCuenta, CodigoUnico = o.CodigoUnico })
                               .FirstOrDefault();
                }
                else
                {
                    account.Error = "Wrong Password or Email";
                }

                HttpResponseMessage response;
                response = Request.CreateResponse(HttpStatusCode.OK, account);
                return response;
            }
        }
        catch (TaskCanceledException ex)
        {

            HttpResponseMessage response;
            response = Request.CreateErrorResponse(HttpStatusCode.BadRequest, ex);
            return response;
        }

    }

Answer 1

在submit的异步API上进行阻塞调用（.Result）可能导致死锁，尤其是在被用作asp.net MVC的情况下，该死锁可能在进行阻塞调用时调用了异步操作。 / p>

使代码一直保持异步。

也请尝试避免在每个请求上创建HttpClinet的实例。这可能会导致插槽用尽。

HttpClient

Answer 2

您可能会因阻塞异步调用而陷入僵局，如this article中所述。这是有问题的行：

private static HttpClient client = new HttpClient();

public async Task<ActionResult> Login(LoginM us) {
    try {
        cuentaM account = new cuentaM();
        var url = "http://localhost:26723/api/Login" + "?email=" + us.email + "&password=" + us.password
        var result = await client.GetAsync(url);
        if (result.IsSuccessStatusCode) {
            account = await result.Content.ReadAsAsync<cuentaM>();
        }

        Session["cuenta"] = account;
        return RedirectToAction("Index", "Home");
    } catch (Exception ex) {
        throw;
    }
}

将account = result.Content.ReadAsAsync<cuentaM>().Result;的方法签名更改为：

Login

然后将有问题的行更改为使用public async Task<ActionResult> Login(LoginM us)而不是await：

.Result

WepApi TaskCanceledException已取消任务。 httpClient

2 个答案: