c# - 存储获取 blob TaskCanceledException

Question

我的应用程序使用 Azure 存储 blob 将文件从远程存储下载到本地计算机。

工作原理:

1. 计算机获取带有 Azure 存储 blob 的 URL(签名 URL)的队列消息。
2. 应用程序发送 GET 来下载文件。这是通过 HttpClient 完成的。
3. 应用逻辑从这里继续。

这是我下载文件的方式:

HttpRequestMessage msg = new HttpRequestMessage(HttpMethod.Get, signedUrl);
HttpClient.Timeout = TimeSpan.FromSeconds(120);
var response = await HttpClient.SendAsync(msg);
response.EnsureSuccessStatusCode();

我发现每天都会有几次出现异常:

System.Threading.Tasks.TaskCanceledException: The operation was canceled. ---> System.IO.IOException: Unable to read data from the transport connection: Operation canceled. ---> System.Net.Sockets.SocketException: Operation canceled --- End of inner exception stack trace --- at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.ThrowException(SocketError error) at System.Net.Sockets.Socket.AwaitableSocketAsyncEventArgs.GetResult(Int16 token) at System.Net.Security.SslStreamInternal.g__InternalFillBufferAsync|38_0[TReadAdapter](TReadAdapter adap, ValueTask1 task, Int32 min, Int32 initial) at System.Net.Security.SslStreamInternal.ReadAsyncInternal[TReadAdapter](TReadAdapter adapter, Memory1 buffer) at System.Net.Http.HttpConnection.SendAsyncCore(HttpRequestMessage request, CancellationToken cancellationToken) --- End of inner exception stack trace --- at System.Net.Http.HttpConnection.SendAsyncCore(HttpRequestMessage request, CancellationToken cancellationToken) at System.Net.Http.HttpConnectionPool.SendWithNtConnectionAuthAsync(HttpConnection connection, HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken) at System.Net.Http.HttpConnectionPool.SendWithRetryAsync(HttpRequestMessage request, Boolean doRequestAuth, CancellationToken cancellationToken) at System.Net.Http.RedirectHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) at System.Net.Http.DecompressionHandler.SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) at System.Net.Http.HttpClient.FinishSendAsyncBuffered(Task1 sendTask, HttpRequestMessage request, CancellationTokenSource cts, Boolean disposeCts) at Polly.Retry.AsyncRetryEngine.ImplementationAsync[TResult](Func3 action, Context context, CancellationToken cancellationToken, ExceptionPredicates shouldRetryExceptionPredicates, ResultPredicates1 shouldRetryResultPredicates, Func5 onRetryAsync, Int32 permittedRetryCount, IEnumerable1 sleepDurationsEnumerable, Func4 sleepDurationProvider, Boolean continueOnCapturedContext) at Polly.AsyncPolicy1.ExecuteAsync(Func3 action, Context context, CancellationToken cancellationToken, Boolean continueOnCapturedContext)

此时，我必须澄清这种行为发生在系统中传递的约 0.1% 的 URL 中。

我怀疑问题出在签名 URL 上。我发现在所有情况下签名的 URL 都是正确的 - 我只需将其放入浏览器中即可正常工作。

现在，当我知道问题不是 URL 本身时，我认为可能是网络问题。因此，通过使用 Polly我添加了 5 次重试，每次重试之间都有指数延迟。最多重试 5 次。延迟公式 - 3^n(其中 n 是重试次数)。在最坏的情况下，它会等待 4 分钟再重试...即使现在 - 仍然是同样的错误。 5 次重试均已使用，但文件未下载。

该怎么办？我还应该检查什么？

Answer 1

似乎是网络问题。我建议您使用Azure存储客户端SDK下载blob。

// Blob SAS URL
string url = "https://storagetest789.blob.core.windows.net/devops/deploy.ps1?sp=r&st=2020-01-21T09:39:06Z&se=2020-01-21T17:39:06Z&spr=https&sv=2019-02-02&sr=b&sig=tyGX6wpgAooOZK2Po2ntukF0fGx3PosSNTgkLlVysrE%3D";
CloudBlockBlob blob = new CloudBlockBlob(new Uri(url));
Console.WriteLine(blob.DownloadText());

您还可以使用 SDK 方法下载到文件或流式传输。 SDK可以处理所有底层的东西。