C#多线程－－获取当前线程ID

【文章标题】: 乱涂C#多线程02

【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】

采用线程池线程执行任务我们无法直接控制线程.有时我们想直接控制线程的行为,那么我们可以创建非线程池线程.

// ThreadDemo.cs
// Author by Yzl

using System;
using System.Threading;

public class ThreadDemo
{
public static void Main(string[] args)
{
Thread t = new Thread(new ThreadStart(ThreadProc));
t.Start();
Console.WriteLine("Priority:" + t.Priority);
Console.WriteLine("ThreadState:" + t.ThreadState);
for (int i = 0; i < 5; i ++)
{
Console.WriteLine("Hello Main");
Thread.Sleep(100);
}
}

private static void ThreadProc()
{
for (int i = 0;i < 5; i ++)
{
Console.WriteLine("Hello ThreadProc");
Thread.Sleep(500);
}
}
}

 

编译运行:

D:\>csc ThreadDemo.cs

Microsoft (R) Visual C# .NET 编译器版本 7.10.6001.4

用于 Microsoft (R) .NET Framework 版本 1.1.4322

版权所有 (C) Microsoft Corporation 2001-2002。保留所有权利。

D:\>ThreadDemo

Hello ThreadProc

Priority:Normal

ThreadState:WaitSleepJoin

Hello Main

Hello Main

Hello Main

Hello Main

Hello Main

Hello ThreadProc

Hello ThreadProc

Hello ThreadProc

Hello ThreadProc

前台线程和后台线程:线程池线程都是后台线程,一般线程创建时默认为前台线程,可以通过Thread.IsBackground属性进行更改.一旦程序中不再有前台线程,Windows将终止该程序.

 

我们先来看看前台线程

 

// ThreadDemo.cs
// Author by Yzl

using System;
using System.Threading;

public class ThreadDemo
{
public static void Main(string[] args)
{
Thread t = new Thread(new ThreadStart(ThreadProc));
t.Name = "CustomThread";
//t.IsBackground = true;
t.Start();
}

private static void ThreadProc()
{
for (int i = 0;i < 5; i ++)
{
Console.WriteLine("Hello ThreadProc");
Thread.Sleep(800);
}
}
}

D:\>csc ThreadDemo.cs

D:\>ThreadDemo

Hello ThreadProc

Hello ThreadProc

Hello ThreadProc

Hello ThreadProc

Hello ThreadProc

奇怪!程序并未调用Thread.Join()方法,自定义线程也一样执行完.正常情况下t.Start()执行完后Main也就终结了,整个程序应该退出才是!

接下来我们测试一下后台线程,将下面代码的注释去掉:

//t.IsBackground = true;

重新运行看效果:

D:\>csc ThreadDemo.cs

D:\>ThreadDemo

D:\>

什么结果也没有!!换句话说,只要有一个前台线程,不管Main上代码是否都已经执行,它也将等待其他前台线程执行完毕才退出.如果Main上的代码都已执行同时不存在前台线程,那么程序自动退出.

同样还有一个问题存在,我们更改一下上面的程序:

// ThreadDemo.cs
// Author by Yzl

using System;
using System.Threading;

public class ThreadDemo
{
public static void Main(string[] args)
{
Thread t = new Thread(new ThreadStart(ThreadProc));
t.Name = "CustomThread";
Thread.CurrentThread.IsBackground = true; // 注意!设置主线程为后台线程!
Console.WriteLine("the t of thread is Background:" + t.IsBackground); // 注意!
t.Start();
}

private static void ThreadProc()
{
for (int i = 0;i < 5; i ++)
{
Console.WriteLine("Hello ThreadProc");
Thread.Sleep(800);
}
}
}

 

编译运行:

D:\>csc ThreadDemo.cs

Microsoft (R) Visual C# .NET 编译器版本 7.10.6001.4

用于 Microsoft (R) .NET Framework 版本 1.1.4322

版权所有 (C) Microsoft Corporation 2001-2002。保留所有权利。

D:\>ThreadDemo

the t of thread is Background:False

D:\>

问题1:如果按我们刚才的理解,t是前台线程,Main理应等待线程t完全执行完毕才是,但是结果却什么也没输出!这是什么缘故?暂时还没研究出答案,待我们深入探讨之后在回头看这个问题

非托管线程是通过线程ID来标识的,托管线程则通过散列代码(Thread.GetHashCode())或名称(Thread.Name)来标识.获取当前线程ID采用AppDomain.GetCurrentThreadId().

示例-获取线程ID

// T.cpp
// Author by Yzl

#include < stdio.h >
#using < mscorlib.dll >
using namespace System::Threading;

#pragma managed
__gc class ThreadDelagate
{
public:
void Start()
{
ThreadStart *ts = new ThreadStart(this,ThreadProc);
Thread* myThread = new Thread(ts);
myThread->Start();
}
private:
void ThreadProc()
{
printf("Thread id:%d",System::AppDomain::GetCurrentThreadId());
}
};

#pragma managed
int main()
{
ThreadDelagate *td = new ThreadDelagate;
td->Start();
}

 

编译运行:

D:\>cl /clr T.cpp

Microsoft (R) C/C++ Optimizing Compiler Version 13.10.3077 for .NET Framework

Copyright (C) Microsoft Corporation 1984-2002. All rights reserved.

T.cpp

Microsoft (R) Incremental Linker Version 7.10.3077

Copyright (C) Microsoft Corporation.  All rights reserved.

/out:T.exe

T.obj

D:\>T

Thread id:1800

D:\>

注意!如果将main更改为:

#pragma unmanaged

int main()

{

    ThreadDelagate *td = new ThreadDelagate;

    td->Start();    

}

编译将得到如下错误:

error C3821: “ThreadDelagate” : 托管类型不能用于非托管函数

error C3169: “td” : 在非托管函数内不能声明托管对象或 __gc 指针

error C3821: “ThreadDelagate” : 托管类型不能用于非托管函数

error C3175: “ThreadDelagate::ThreadDelagate” : 不能从非托管函数“main”调用托管类型的方法

error C3821: “td” : 托管类型不能用于非托管函数

error C3175: “ThreadDelagate::Start” : 不能从非托管函数“main”调用托管类型的方法

原因我就不多讲.很明朗!因此,如果要操纵托管线程ID,需先把它保存起来,然后在非托管代码中进行应用.

示例-枚举非托管线程(ProcessThread表示操作系统进程线程)

// ProcessThreadDemo.cs
// Author by Yzl

using System;
using System.Diagnostics;

public class ProcessThreadDemo
{
public static void Main(string[] args)
{
Console.ReadLine();
ProcessThreadCollection ptCollection = Process.GetCurrentProcess().Threads;
Console.WriteLine("{0} threads in process",ptCollection.Count);
foreach (ProcessThread pt in ptCollection)
{
Console.WriteLine("ID:{0},State:{1},Priority:{2}",pt.Id,pt.ThreadState,pt.PriorityLevel);
}
}
}

 

编译运行:

D:\>ProcessThreadDemo

h

7 threads in process

ID:3700,State:Running,Priority:Normal

ID:1076,State:Wait,Priority:Normal

ID:452,State:Wait,Priority:Highest

ID:2292,State:Wait,Priority:Normal

ID:3872,State:Wait,Priority:Normal

ID:2952,State:Wait,Priority:Normal

ID:996,State:Wait,Priority:Normal

通过枚举的方式我们发现该程序存在7个线程,但是在运行初期,我们通过任务管理器发现它的线程数才3个!这是什么原因呢?原来在枚举进程线程的操作实际上会使CLR创建更多的线程,用以执行此枚举操作!!

<续>

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