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):

C#多线程技术总结(同步)

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

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