如何使用Task.WhenAny并实现重试 [英] How to use Task.WhenAny and implement retry

问题描述

我有一个解决方案，可以创建多个基于I/O的任务，并且我正在使用Task.WhenAny()来管理这些任务.但是通常许多任务会由于网络问题或请求节流等原因而失败.

I have a solution that creates multiple I/O based tasks and I'm using Task.WhenAny() to manage these tasks. But often many of the tasks will fail due to network issue or request throttling etc.

在使用Task.WhenAny()方法时，似乎找不到能够使我成功重试失败任务的解决方案.

I can't seem to find a solution that enables me to successfully retry failed tasks when using a Task.WhenAny() approach.

这是我在做什么:

var tasks = new List<Task<MyType>>();
foreach(var item in someCollection)
{
   task.Add(GetSomethingAsync());
}
while (tasks.Count > 0)
{
   var child = await Task.WhenAny(tasks);
   tasks.Remove(child);
   ???
}

因此上述结构可用于完成任务，但是我还没有找到处理和重试失败任务的方法. await Task.WhenAny引发AggregateException，而不是允许我检查任务状态.在异常处理程序中时，我不再有任何方法可以重试失败的任务.

So the above structure works for completing tasks, but I haven't found a way to handle and retry failing tasks. The await Task.WhenAny throws an AggregateException rather than allowing me to inspect a task status. When In the exception handler I no longer have any way to retry the failed task.

推荐答案

我相信重试 个任务然后替换Task.WhenAny -in-a-loop反模式会更容易与Task.WhenAll

I believe it would be easier to retry within the tasks, and then replace the Task.WhenAny-in-a-loop antipattern with Task.WhenAll

例如，使用 Polly :

E.g., using Polly:

var tasks = new List<Task<MyType>>();
var policy = ...; // See Polly documentation
foreach(var item in someCollection)
  tasks.Add(policy.ExecuteAsync(() => GetSomethingAsync()));
await Task.WhenAll(tasks);

或更简洁地说:

var policy = ...; // See Polly documentation
var tasks = someCollection.Select(item => policy.ExecuteAsync(() => GetSomethingAsync()));
await Task.WhenAll(tasks);

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