.Net多线程编程（误用点分析）

public static void Error()
{
   for(int i=0;i<10;i++)
   {
    Task.Run(() => { Console.WriteLine("{0}", i); });
   }
}

public static void Right()
{
   for (int i = 0; i < 10; i++)
   {
    int temp = i;
    Task.Run(() => { Console.WriteLine("{0}", temp); });
   }
}

public static void Error()
{
   using (StreamReader sr = new StreamReader(@"D:\说明.txt", Encoding.Default))
   {
    Task.Run(() => { Console.WriteLine("输出：{0}",sr.ReadLine()); });
   }
}

public static void Right()
{
   using (StreamReader sr = new StreamReader(@"D:\说明.txt", Encoding.Default))
   {
    var task = Task.Run(() => { Console.WriteLine("输出：{0}", sr.ReadLine()); });
    task.Wait();
   }
}

public static void Error()
{
   ManualResetEvent[] manualEvents = new ManualResetEvent[65];

   try
   {
    for (int i = 0; i < 65; i++)
    {
     var temp = i;
     Task.Run(() =>
     {
      manualEvents[temp] = new ManualResetEvent(false);
      Console.WriteLine("{0}", temp);
      manualEvents[temp].Set();
     });
    }
    WaitHandle.WaitAll(manualEvents);
   }
   catch (Exception ae)
   {
    Console.WriteLine(ae.Message);
   }
}

try
{
    var task = Task.Run(() => { throw new Exception("抛异常"); });
    //如果将下面这行代码注掉，则无法抛出异常
    task.Wait();
}
catch(Exception ex)
{
    Console.WriteLine(ex.Message);
}

public static void CatchException()
{
   try
   {
    Console.WriteLine("开始");
    var task = Task.Run(() =>
    {
     //throw new Exception("抛异常"); 
    });
    //注掉下面这行代码，观察异常结果
    //task.Wait();
    task.Dispose();
    Console.WriteLine("结束");
   }
   catch(Exception ex)
   {
    Console.WriteLine(ex.Message);
   }
}

private static readonly Object LockedObj1 = new object();
private static readonly Object LockedObj2 = new object();
public static void LockShow()
{
   var task1 = Task.Run(() => 
   {
    lock (LockedObj1)
    {
     Console.WriteLine("get LockedObj1");
     lock (LockedObj2)
     {
      Console.WriteLine("get LockedObj2....");
     }
    }
   });
   var task2 = Task.Run(() =>
   {
    lock (LockedObj2)
    {
     Console.WriteLine("get LockedObj2");
     lock (LockedObj1)
     {
      Console.WriteLine("get LockedObj1....");
     }
    }
   });
}

public static void Func()
{
   string s = "ASDFGH";
   Parallel.Invoke(
    () => { s = s.Replace("A", "1"); s = s.Replace("S", "1s"); }, 
    () => { s = s.Replace("A", "2"); s = s.Replace("S", "2s"); }, 
    () => { s = s.Replace("A", "3"); });
   Console.WriteLine(s);
}

public static void Func()
{
   ParallelOptions po = new ParallelOptions();
   //超额申请，处理器只有4个逻辑内核，结果设置并行度为10且是个逻辑内核均在工作，等待的任务数量大于0.
   po.MaxDegreeOfParallelism = 10;
   //申请不足，处理器有4个逻辑内核，却指定并行度为3，还有一个空闲的内核没有被占用(也有可能被其他线程占用，这里假设在指定并行度为3的情况下，另一个内核空闲)
   po.MaxDegreeOfParallelism = 3;
   List<int> list = new List<int>();
   Parallel.ForEach(list, po, m =>
   {
    //业务
   });
}