c# 并行与异步

本文主要是介绍c# 并行与异步，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

c# Parallel.For 设置最大并行个数

Parallel.Options

MaxDegreeOfParallelism 最大并行度

static void Main(string[] args)
{ParallelOptions op = new ParallelOptions{MaxDegreeOfParallelism = 4};var bag = new ConcurrentBag<int>();Parallel.For(0, 10, op, (i, state) =>{Thread.Sleep(1000);if (i > 5)bag.Add(i);Console.WriteLine(i);});Console.WriteLine(bag.Count);
}

ParallelLoopState

.Stop终止当前运行

static void Main(string[] args)
{ParallelOptions op = new ParallelOptions{MaxDegreeOfParallelism = 4};var bag = new ConcurrentBag<int>();Parallel.For(0, 10, op, (i, state) =>{Thread.Sleep(1000);if (i > 5){bag.Add(i);state.Stop();return;}Console.WriteLine(i);});Console.WriteLine(bag.Count);
}

异步

Task输入验证 - 判断参数为空

参数为空异常会同步抛出，不会导致运行失败的任务
ComputeLengthAsync为非 async 方法，函数里抛出异常不会被包装在Task内

static Task<int> ComputeLengthAsync(string text)
{if (text == null){throw new ArgumentNullException("text");}return ComputeLengthAsyncImpl(text);
}static async Task<int> ComputeLengthAsyncImpl(string text)
{await Task.Delay(500);return text.Length;
}

调用

此处不会打印到 Fetched the task，

var task = ComputeLengthAsync(null);
Console.WriteLine("Fetched the task");
int length = task.Result;
Console.WriteLine("Length: {0}", length);

Task 取消

此处 task.Status为 Canceled

static async Task TaskCanceled()
{throw new OperationCanceledException();
}

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