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[ASP.net教程]C#多线程技术总结(同步)


二、串行(同步):

1.lock、Monitor--注意锁定的对象必需是引用类型(string类型除外)

示例:

    private static object syncObject = new object();    private static void TaskWork(object i)    {      Console.WriteLine("我是任务:{0}",i);      lock (syncObject)      {        Thread.Sleep(1000);        Console.WriteLine("我是任务:{0},线程ID:{1}",i,Thread.CurrentThread.ManagedThreadId);      }      try      {        Monitor.Enter(syncObject);        Console.WriteLine("我是任务:{0},线程ID:{1}", i, Thread.CurrentThread.ManagedThreadId);      }      finally      {        Monitor.Exit(syncObject);      }    }//调用Task.Factory.StartNew(TaskWork,1);Task.Factory.StartNew(TaskWork, 2);

2.Interlocked

示例:

      int i=1;      Interlocked.Increment(ref i); //增量+1=2;      Console.WriteLine("i当前的值:{0}", i);      Interlocked.Decrement(ref i); //减量-1=0;      Console.WriteLine("i当前的值:{0}", i);      Interlocked.Exchange(ref i, 2);//赋值=2;      Console.WriteLine("i当前的值:{0}",i);      Interlocked.CompareExchange(ref i, 10, 2);//比较交换值,当i=2时,则将i赋值为10;      Console.WriteLine("i当前的值:{0}", i);

3.Mutex--可以实现进程间的同步,甚至是两个远程进程间的同步

示例:

      var t1 = new Task(() =>      {        Console.WriteLine("我是第一个任务!");        Mutex m = new Mutex(false, "test");        m.WaitOne();        Console.WriteLine("第一个任务完成!");        m.ReleaseMutex();      });      var t2 = new Task(() =>      {        Console.WriteLine("我是第二个任务!");        Mutex m = new Mutex(false, "test");        m.WaitOne();        Console.WriteLine("第二个任务完成!");        m.ReleaseMutex();      });      t1.Start();      t2.Start();

 4.ReaderWriterLock 、ReaderWriterLockSlim--如果在某一时刻资源并没有获取写的独占权,那么可以获得多个读的访问权,单个写入的独占权,如果某一时刻已经获取了写入的独占权,那么其它读取的访问权必须进行等待. 

示例:

    static ReaderWriterLock rwLock = new ReaderWriterLock();    static void Read(object state)    {      Console.WriteLine("我是读线程,线程ID是:{0}",Thread.CurrentThread.ManagedThreadId);      rwLock.AcquireReaderLock(Timeout.Infinite);//无限期等待,需要显式调用ReleaseReaderLock释放锁      var readList = state as IEnumerable<int>;      foreach (int item in readList)      {        Console.WriteLine("读取当前的值为:{0}", item);        Thread.Sleep(500);      }      Console.WriteLine("读完成,线程ID是:{0}", Thread.CurrentThread.ManagedThreadId);      rwLock.ReleaseReaderLock();          }    static void Write(object state)    {      Console.WriteLine("我是写线程,线程ID是:{0}", Thread.CurrentThread.ManagedThreadId);      rwLock.AcquireWriterLock(Timeout.Infinite); //无限期等待,需要显式调用ReleaseWriterLock释放锁      var writeList = state as List<int>;      int lastCount=writeList.Count();      for (int i = lastCount; i <= 10+lastCount; i++)      {        writeList.Add(i);        Console.WriteLine("写入当前值:{0}",i);        Thread.Sleep(500);      }      Console.WriteLine("写完成,线程ID是:{0}", Thread.CurrentThread.ManagedThreadId);      rwLock.ReleaseWriterLock();    }  //调用:      var rwList = new List<int>();      var t1 = new Thread(Write);      var t2 = new Thread(Read);      var t3 = new Thread(Write);      var t4 = new Thread(Read);            t1.Start(rwList);      t2.Start(rwList);      t3.Start(rwList);      t4.Start(rwList);

 


5.SynchronizationAttribute--确保某个类的实例在同一时刻只能被一个线程访问,类的定义要求:A.类上必需标记SynchronizationAttribute特性,B.类必需继承自System.ContextBoundObject对象

示例:

  [Synchronization(SynchronizationAttribute.REQUIRED,true)]  public class Account : System.ContextBoundObject  {    private static int _balance;    public int Blance    {      get      {        return _balance;      }    }    public Account()    {      _balance = 1000;    }    public void WithDraw(string name,object money)    {      if ((int)money <= _balance)      {        Thread.Sleep(2000);        _balance = _balance - (int)money;        Console.WriteLine("{0} 取钱成功!余额={1}", name, _balance);      }      else      {        Console.WriteLine("{0} 取钱失败!余额不足!", name);      }    }  }//调用:      var account = new Account();      Parallel.Invoke(() =>      {        account.WithDraw("张三",600);      }, () =>      {        account.WithDraw("李四",600);      });

6.MethodImplAttribute--使整个方法上锁,直到方法返回,才释放锁

示例:

  public class Account  {    private static int _balance;    public int Blance    {      get      {        return _balance;      }    }    public Account()    {      _balance = 1000;    }    [MethodImpl(MethodImplOptions.Synchronized)]    public void WithDraw(string name,object money)    {      if ((int)money <= _balance)      {        Thread.Sleep(2000);        _balance = _balance - (int)money;        Console.WriteLine("{0} 取钱成功!余额={1}", name, _balance);      }      else      {        Console.WriteLine("{0} 取钱失败!余额不足!", name);      }    }  }//调用      var account = new Account();      Parallel.Invoke(() =>      {        account.WithDraw("张三",600);      }, () =>      {        account.WithDraw("李四",600);      });

7.AutoResetEvent、ManualResetEvent、ManualResetEventSlim--调用WaitOne、WaitAny或WaitAll来使线程等待事件,调用Set方法发送信号,事件将变为终止状态,等待的线程被唤醒

示例:

      AutoResetEvent arEvent = new AutoResetEvent(false);//默认为无信号,处于非终止状态      Task.Factory.StartNew((o) => {        for (int i = 1; i <= 10; i++)        {          Console.WriteLine("循环第{0}次",i);        }        arEvent.Set();//发送信号,处于终止状态      },arEvent);      arEvent.WaitOne();//等待信号,收到信号后则继续下面的执行      Console.WriteLine("我是主线程,我继续执行!");      Console.Read();

 8.Sempaphore、SemaphoreSlim(不可跨进程)--信号量,可实现线程、进程间同步

示例:

  public class WashRoom  {    private readonly Semaphore sem;    public WashRoom(int maxUseableCount)    {      sem = new Semaphore(maxUseableCount, maxUseableCount, "WC");    }    public void Use(int i)    {      Task.Factory.StartNew(() =>        {          Console.WriteLine("第{0}个人等待进入", i);          // WaitOne:如果还有“空位”,则占位,如果没有空位,则等待;          sem.WaitOne();          Console.WriteLine("第{0}个人成功进入,使用中", i);          // 模拟线程执行了一些操作          Thread.Sleep(100);          Console.WriteLine("第{0}个人用完,离开了", i);          // Release:释放一个“空位”          sem.Release();        });    }  }//调用:      var wc = new WashRoom(5);      for (int i = 1; i <= 7; i++)      {        wc.Use(i);      }

9.Barrier--屏障,使多个任务能够采用并行方式依据某种算法在多个阶段中协同工作,即:将一个阶段的事情分成多个线程来异步执行,执行完毕后再同时进入下一个阶段

示例:

      int taskSize = 5;      Barrier barrier = new Barrier(taskSize, (b) =>      {        Console.WriteLine(string.Format("{0}当前阶段编号:{1}{0}", "-".PadRight(15, '-'), b.CurrentPhaseNumber));      });      var tasks = new Task[taskSize];      for (int i = 0; i < taskSize; i++)      {        tasks[i] = Task.Factory.StartNew((n) =>        {          Console.WriteLine("Task : #{0}  ----> 处理了第一部份数据。", n);          barrier.SignalAndWait();          Console.WriteLine("Task : #{0}  ----> 处理了第二部份数据。", n);          barrier.SignalAndWait();          Console.WriteLine("Task : #{0}  ----> 处理了第三部份数据。", n);          barrier.SignalAndWait();        }, i);      }      Task.WaitAll(tasks);

10.SpinLock--自旋锁,仅限锁定的时间较短

示例:

      SpinLock sLock = new SpinLock();      int num = 0;      Action action = () =>      {        bool lockTaken = false;        for (int i = 0; i < 10; i++)        {          lockTaken = false;          try          {            sLock.Enter(ref lockTaken);            Console.WriteLine("{0}+1={1} ---线程ID:[{2}]", num, ++num,Thread.CurrentThread.ManagedThreadId);            Thread.Sleep(new Random().Next(9));          }          finally          {            //真正获取之后,才释放            if (lockTaken) sLock.Exit();          }        }      };//多线程调用:      Parallel.Invoke(action, action, action);      Console.WriteLine("合计:{0}", num);

11.SpinWait--自旋等待,轻量级

      Thread.Sleep(1000);//线程等待1S;      Console.WriteLine(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"));      SpinWait.SpinUntil(() => false, 1000);//自旋等待1S      Console.WriteLine(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"));      Thread.SpinWait(100000);//指定CPU的循环次数,时间间隔处决于处理器的运行速度,一般不建议使用      Console.WriteLine(DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss.fff"));

12.CountdownEvent--与Sempaphore功能类似,但CountdownEvent支持动态调整信号计数

 示例:

    static void TimeLimitShopping(int custCount,int times,CountdownEvent countdown)    {      var customers = Enumerable.Range(1, custCount);      foreach (var customer in customers)      {        int currentCustomer = customer;        Task.Factory.StartNew(()=>        {          SpinWait.SpinUntil(() => false, 1000);          Console.WriteLine("第{0}波客户购买情况:Customer-{1}-已购买.", times, currentCustomer);          countdown.Signal();        });        //countdown.AddCount();      }    }//调用:var countdown = new CountdownEvent(5);        TimeLimitShopping(5, 1, countdown);        countdown.Wait();        countdown.Reset(10);        TimeLimitShopping(10, 2, countdown);        countdown.Wait();        countdown.Reset(20);        TimeLimitShopping(20, 3, countdown);        countdown.Wait();

 最后分享在System.Collections.Concurrent命名空间下的几个并发集合类:

ConcurrentBag<T>:表示线程安全的无序集合;

ConcurrentDictionary<T>:表示线程安全的多个键值对集合;

ConcurrentQueue<T>:表示线程安全的先进先出集合;

ConcurrentStack<T>:表示线程安全的后进先出集合;

线程的几个状态(以下图片来源于这篇文章:http://www.cnblogs.com/edisonchou/p/4848131.html):

参考以下相关文章:

归纳一下:C#线程同步的几种方法

C#编程总结(三)线程同步