【文章标题】: 乱涂C#多线程04
【文章作者】: 有酒醉
【作者邮箱】: wuqr32@sina.com
【下载地址】: 自己搜索下载
【作者声明】: 只是感兴趣，没有其他目的。失误之处敬请诸位大侠赐教!
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【详细过程】
三、同步变量访问
数据同步容易造成数据的破坏.虽然说数据同步可能会破坏我们的程序,但是它不会破坏类型安全性.这是因为装载诸如指针等基本类型总是基本操作,所以不会破坏托管指针和对象引用.
【文章作者】: 有酒醉
【作者邮箱】: wuqr32@sina.com
【下载地址】: 自己搜索下载
【作者声明】: 只是感兴趣，没有其他目的。失误之处敬请诸位大侠赐教!
--------------------------------------------------------------------------------
【详细过程】
三、同步变量访问
数据同步容易造成数据的破坏.虽然说数据同步可能会破坏我们的程序,但是它不会破坏类型安全性.这是因为装载诸如指针等基本类型总是基本操作,所以不会破坏托管指针和对象引用.
lock 语句用于获取某个给定对象的互斥锁,执行一个语句,然后释放该锁.我们先研究下lock的内部实现方式
// LockDemo.cs// Author by Yzlusing System;using System.Threading;public class LockDemo
...{
public static void Main(string[] args)
...{ ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc),"Yzl01"); ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc),"Yzl02"); ThreadPool.QueueUserWorkItem(new WaitCallback(ThreadProc),"Yzl03"); Console.ReadLine();
} private static void ThreadProc(object state) ...{ Thread.Sleep(500); Console.WriteLine("Current Object:"+state); lock(x.GetType()) ...{ x = System.AppDomain.GetCurrentThreadId(); Console.WriteLine("x="+x); } } private static int x ;
}编译运行:
E:/>csc LockDemo.cs
E:/>csc LockDemo.cs
E:/>LockDemo
Current Object:Yzl01
x=2212
Current Object:Yzl02
x=2212
Current Object:Yzl03
x=2444
exit
Current Object:Yzl01
x=2212
Current Object:Yzl02
x=2212
Current Object:Yzl03
x=2444
exit
反汇编查看内部结构:
IL_001a: ldsfld int32 LockDemo::xIL_001f: box [mscorlib]System.Int32IL_0024: call instance class [mscorlib]System.Type [mscorlib]System.Object::GetType()IL_0029: dupIL_002a: stloc.0IL_002b: call void [mscorlib]System.Threading.Monitor::Enter(object).try...{ IL_0030: call int32 [mscorlib]System.AppDomain::GetCurrentThreadId() IL_0035: stsfld int32 LockDemo::x IL_003a: ldstr "x=" IL_003f: ldsfld int32 LockDemo::x IL_0044: box [mscorlib]System.Int32 IL_0049: call string [mscorlib]System.String::Concat(object, object) IL_004e: call void [mscorlib]System.Console::WriteLine(string) IL_0053: leave.s IL_005c} // end .tryfinally...{ IL_0055: ldloc.0 IL_0056: call void [mscorlib]System.Threading.Monitor::Exit(object) IL_005b: endfinally} // end handler我们很容易观察出lock实际上是应用了Monitor来进行同步变量的访问.同时也注意到了Monitor::Exit(object)放在finally中保证了同步锁的释放.
C++中没有等效于C# lock 语句,如果用C++编写代码,那么需要显式调用Monitor方法.
示例 -- C++ 中应用lock
// CLockDemo.cpp// Author by Yzl#using < mscorlib.dll >using namespace System;using namespace System::Threading;#pragma managed__gc class CLockDemo...{ public: static void ThreadProc(Object* state) ...{ Thread::Sleep(1000); Console::WriteLine(S"Current Object:{0}",state->ToString()); Object *iObj = __box(x); Type *iType = iObj->GetType(); try ...{ //Lock the x Monitor::Enter(iType); x = AppDomain::GetCurrentThreadId(); Console::WriteLine(S"x={0}",x.ToString()); } catch(Exception *ex) ...{ Console::WriteLine(ex->ToString()); } __finally ...{ Monitor::Exit(iType); } } private: static int x;};#pragma managedint main(void)...{ ThreadPool::QueueUserWorkItem(new WaitCallback(0,CLockDemo::ThreadProc),new String("Yzl01")); ThreadPool::QueueUserWorkItem(new WaitCallback(0,CLockDemo::ThreadProc),new String("Yzl02")); ThreadPool::QueueUserWorkItem(new WaitCallback(0,CLockDemo::ThreadProc),new String("Yzl03")); Console::ReadLine();}编译运行:
E:/>cl ClockDemo.cpp /clr
E:/>cl ClockDemo.cpp /clr
E:/>CLockDemo
Current Object:Yzl01
x=2644
Current Object:Yzl02
x=2660
Current Object:Yzl03
x=2644
exit
Current Object:Yzl01
x=2644
Current Object:Yzl02
x=2660
Current Object:Yzl03
x=2644
exit
我们将Monitor::Exit(iType)注释掉,观察一下会有什么结果:
E:/>cl ClockDemo.cpp /clr
E:/>cl ClockDemo.cpp /clr
E:/>ClockDemo
Current Object:Yzl01
x=2672
Current Object:Yzl02
Current Object:Yzl03
x=2672
Current Object:Yzl01
x=2672
Current Object:Yzl02
Current Object:Yzl03
x=2672
到这里程序无法运行下去,停滞不前.这是由于2672号线程并未释放对象锁所造成的.同时我们也发现Object:Yzl01,Object:Yzl03采用了同一线程池中的线程运行自己的任务.
<续>
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【版权声明】: 本文原创于厦门, 转载请注明作者并保持文章的完整, 谢谢!
【版权声明】: 本文原创于厦门, 转载请注明作者并保持文章的完整, 谢谢!
2007年03月01日 14:10:15