dotnet Core 異步任務

一、使用線程池中線程的任務啟動方式

線程池提供了一個后台線程的池，獨自管理線程，按需增加或減少線程池中的線程數。線程池中的線程用於執行一些動作后仍然返回線程池中。

• 示例:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.IO;

namespace TaskSamples
{
  class Program
  {
    static void Main()
    {
      TasksUsingThreadPool();
      Console.ReadLine();
    }

    

    static void TasksUsingThreadPool()
    {
      var tf = new TaskFactory();
      Task t1 = tf.StartNew(TaskMethod, "using a task factory");

      Task t2 = Task.Factory.StartNew(TaskMethod, "factory via a task");

      var t3 = new Task(TaskMethod, "using a task constructor and Start");
      t3.Start();

      Task t4 = Task.Run(() => TaskMethod("using the Run method"));

    }

    static object taskMethodLock = new object();
    static void TaskMethod(object title)
    {
      lock (taskMethodLock)
      {
        Console.WriteLine(title);
        Console.WriteLine("Task id: {0}, thread: {1}",
          Task.CurrentId == null ? "no task" : Task.CurrentId.ToString(),
          Thread.CurrentThread.ManagedThreadId);
        Console.WriteLine("is pooled thread: {0}", Thread.CurrentThread.IsThreadPoolThread);
        Console.WriteLine("is background thread: {0}", Thread.CurrentThread.IsBackground);
        Console.WriteLine();
      }
    }
  }
}

1. 實例化TaskFactory類，將要執行的方法作為參數傳遞給實例的StartNew方法

var tf = new TaskFactory();
Task t1 = tf.StartNew(TaskMethod, "using a task factory");

2. 使用Task類的靜態屬性TaskFactory訪問TaskFactory,並調用其StartNew方法

Task t2 = Task.Factory.StartNew(TaskMethod, "factory via a task");

3. 使用Task類的構造函數實例化Task對象，並調用其Start方法

var t3 = new Task(TaskMethod, "using a task constructor and Start");
t3.Start();

4. 調用Task類的靜態方法Run,參數為一個Action委托

Task t4 = Task.Run(() => TaskMethod("using the Run method"));