在 500 响应之后，在重新启动进程之前不会再次发送请求

如何解决在 500 响应之后，在重新启动进程之前不会再次发送请求

我正在使用 Polly 来实现请求重试。但是，对于请求返回 500 响应后，Polly 不仅在重试时不发送请求，而且在重新启动进程之前根本不发送请求。相反，Polly 只是等到超时。代码如下：

var timeoutPolicy = TimeoutPolicy
    .TimeoutAsync<HttpResponseMessage>(c => c.GetTimeout() ?? TimeSpan.FromSeconds(30)); //timeout para cada intento

var retryPolicy = HttpPolicyExtensions
    .HandleTransientHttpError()
    .Or<TimeoutRejectedException>() //tirado por la TimeoutPolicy
    .WaitAndRetryAsync(new[] { TimeSpan.FromSeconds(1),TimeSpan.FromSeconds(5),TimeSpan.FromSeconds(10) });

var policyHandler = new PolicyHandler(Policy.WrapAsync(retryPolicy,timeoutPolicy));

如何修复代码，让 Polly 在 500 次重试以及后续请求时实际发送请求？

解决方法

错误是由以下issue

引起的

这是我修复它的方式：

var retryPolicy = HttpPolicyExtensions
    .HandleTransientHttpError()
    .Or<TimeoutRejectedException>() //tirado por la TimeoutPolicy
    .WaitAndRetryAsync(new[] 
      { 
        TimeSpan.FromSeconds(1),TimeSpan.FromSeconds(5),TimeSpan.FromSeconds(10) 
      },onRetry: (x,_) =>
      {
          //dispose response when retrying
          x.Result?.Dispose();
      });

,

我确实认为应用程序崩溃与这些政策无关。

我已经用一些调试日志修改了你的代码，如下所示：

public static readonly HttpClient client = new HttpClient();
public static async Task Main(string[] args)
{
    var sw = Stopwatch.StartNew();
    Console.WriteLine($"{sw.Elapsed.Seconds}: Application starts");

    var timeoutPolicy = TimeoutPolicy
        .TimeoutAsync<HttpResponseMessage>(
            TimeSpan.FromSeconds(30),onTimeoutAsync: (ctx,ts,t) => {
                Console.WriteLine($"{sw.Elapsed.Seconds}: Timeout has occurred");
                return Task.CompletedTask;
        });

    var retryPolicy = HttpPolicyExtensions
        .HandleTransientHttpError()
        .Or<TimeoutRejectedException>() 
        .WaitAndRetryAsync(
            new[] { TimeSpan.FromSeconds(1),TimeSpan.FromSeconds(10) },onRetryAsync: (dr,ts) => {
                Console.WriteLine($"{sw.Elapsed.Seconds}: Retry will be triggered");
                return Task.CompletedTask;
            });

    var strategy = Policy.WrapAsync(retryPolicy,timeoutPolicy);
    await strategy.ExecuteAsync(async (ct) => {
        var response = await client.GetAsync("https://httpstat.us/500");
        Console.WriteLine($"{sw.Elapsed.Seconds}: Response has been received");
        return response;
    },CancellationToken.None);

    Console.WriteLine($"{sw.Elapsed.Seconds}: Application finishes");
}

• 每当 httpClient 收到响应时，它都会打印 Response has been received
  • 我仅将 httpstat.us 用于测试目的
• 每当 httpClient 在 30 秒内没有收到响应时，它就会打印 Timeout has occurred
• 只要重试策略应该被触发但在延迟惩罚之前，它就会打印 Retry will be triggered
• 每当发出所有重试但均未成功或其中一个请求成功时，它会打印 Application finishes

使用当前设置，输出将如下所示：

1: Response has been received
1: Retry will be triggered
2: Response has been received
2: Retry will be triggered
8: Response has been received
8: Retry will be triggered
18: Response has been received
18: Application finishes

如您所见，我们发出了 4 次请求（一次初始和 3 次重试），但没有运气。但最终应用程序继续工作。