如何使用异步方法正确编写 Parallel.For [英] How to correctly write Parallel.For with async methods

问题描述

我将如何构建下面的代码以便调用异步方法?

How would I structure the code below so that the async method gets invoked?

Parallel.For(0, elevations.Count(), delegate(int i)
{
   allSheets.AddRange(await BuildSheetsAsync(userID, elevations[i], includeLabels));
});

推荐答案

Parallel.For() 不适用于 async 方法.如果您不需要限制并行度(即您可以同时执行所有任务)，您可以简单地启动所有Task然后等待它们完成:

Parallel.For() doesn't work well with async methods. If you don't need to limit the degree of parallelism (i.e. you're okay with all of the tasks executing at the same time), you can simply start all the Tasks and then wait for them to complete:

var tasks = Enumerable.Range(0, elevations.Count())
    .Select(i => BuildSheetsAsync(userID, elevations[i], includeLabels));
List<Bitmap> allSheets = (await Task.WhenAll(tasks)).SelectMany(x => x).ToList();

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