我对async / await如何作为并行工作感到困惑所以我在这里制作了一个测试代码：
我尝试用列表模拟发送6个任务.
每个任务都将执行3个其他子任务.
我尝试用列表模拟发送6个任务.
每个任务都将执行3个其他子任务.
你可以复制/粘贴测试
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
namespace ConsoleApplication1
{
class Program
{
static void Main(string[] args)
{
//job simulation
Func<int,string,Tuple<int,string>> tc = Tuple.Create;
var input = new List<Tuple<int,string>>{
tc( 6000,"task 1" ),tc( 5000,"task 2" ),tc( 1000,"task 3" ),"task 4" ),"task 5" ),"task 6" )
};
List<Tuple<int,string>> JobsList = new List<Tuple<int,string>>(input);
//paralelism atempt
List<Task> TaskLauncher = new List<Task>();
Parallel.ForEach<Tuple<int,string>>(JobsList,item => JobDispatcher(item.Item1,item.Item2));
Console.ReadLine();
}
public static async Task JobDispatcher(int time,string query)
{
List<Task> TList = new List<Task>();
Task<string> T1 = SubTask1(time,query);
Task<string> T2 = SubTask2(time,query);
Task<string> T3 = SubTask3(time,query);
TList.Add(T1);
TList.Add(T2);
TList.Add(T3);
Console.WriteLine("{0} Launched ",query);
await Task.WhenAll(TList.ToArray());
Console.WriteLine(T1.Result);
Console.WriteLine(T2.Result);
Console.WriteLine(T3.Result);
}
public static async Task<string> SubTask1(int time,string query)
{
//somework
Thread.Sleep(time);
return query + "Finshed SubTask1";
}
public static async Task<string> SubTask2(int time,string query)
{
//somework
Thread.Sleep(time);
return query + "Finshed SubTask2";
}
public static async Task<string> SubTask3(int time,string query)
{
//somework
Thread.Sleep(time);
return query + "Finshed SubTask3";
}
}
}
理想情况下,我应该阅读：
task 1 launched task 2 launched task 3 launched task 4 launched task 5 launched task 6 launched
然后在这一点上所有任务都运行6 * 3 = 18个线程同时运行
但它不是发生在这里的东西似乎执行同步.
结果如下：
什么是编写可以启动任务和子任务作为18并行线程与异步/等待的东西的方法是什么？
解决方法
试试这个示例代码.请注意,它在大约6秒内完成,这表明所有任务都是异步运行的：
using System;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;
namespace ConsoleApplication1
{
class Program
{
static void Main()
{
// ThreadPool throttling may cause the speed with which
// the threads are launched to be throttled.
// You can avoid that by uncommenting the following line,// but that is considered bad form:
// ThreadPool.SetMinThreads(20,20);
var sw = Stopwatch.StartNew();
Console.WriteLine("Waiting for all tasks to complete");
RunWorkers().Wait();
Console.WriteLine("All tasks completed in " + sw.Elapsed);
}
public static async Task RunWorkers()
{
await Task.WhenAll(
JobDispatcher(6000,"task 1"),JobDispatcher(5000,"task 2"),JobDispatcher(4000,"task 3"),JobDispatcher(3000,"task 4"),JobDispatcher(2000,"task 5"),JobDispatcher(1000,"task 6")
);
}
public static async Task JobDispatcher(int time,string query)
{
var results = await Task.WhenAll(
worker(time,query + ": Subtask 1"),worker(time,query + ": Subtask 2"),query + ": Subtask 3")
);
Console.WriteLine(string.Join("\n",results));
}
static async Task<string> worker(int time,string query)
{
return await Task.Run(() =>
{
Console.WriteLine("Starting worker " + query);
Thread.Sleep(time);
Console.WriteLine("Completed worker " + query);
return query + ": " + time + ",thread id: " + Thread.CurrentThread.ManagedThreadId;
});
}
}
}
以下是在RunWorkers()中使用一系列任务的方法：
public static async Task RunWorkers()
{
Task[] tasks = new Task[6];
for (int i = 0; i < 6; ++i)
tasks[i] = JobDispatcher(1000 + i*1000,"task " + i);
await Task.WhenAll(tasks);
}
