【文章標題】: 亂塗C#多執行緒02

【文章作者】: 有酒醉

【作者郵箱】: [email protected]

【下載地址】: 自己搜尋下載

【作者宣告】: 只是感興趣，沒有其他目的。失誤之處敬請諸位大俠賜教!

【詳細過程】

採用執行緒池執行緒執行任務我們無法直接控制執行緒.有時我們想直接控制執行緒的行為,那麼我們可以建立非執行緒池執行緒.

// 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);  
        }  
    }  
}

編譯執行:

D:>csc ThreadDemo.cs

Microsoft (R) Visual C# .NET 編譯器版本 7.10.6001.4

用於 Microsoft (R) .NET Framework 版本 1.1.4322

版權所有 (C) Microsoft Corporation 2001-2002。保留所有權利。

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

前臺執行緒和後臺執行緒:執行緒池執行緒都是後臺執行緒,一般執行緒建立時預設為前臺執行緒,可以通過Thread.IsBackground屬性進行更改.一旦程式中不再有前臺執行緒,Windows將終止該程式.

我們先來看看前臺執行緒

// 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!程式並未呼叫Thread.Join()方法,自定義執行緒也一樣執行完.正常情況下t.Start()執行完後Main也就終結了,整個程式應該退出才是!

接下來我們測試一下後臺執行緒,將下面程式碼的註釋去掉:

//t.IsBackground = true;

重新執行看效果:

D:>csc ThreadDemo.cs

D:>ThreadDemo

D:>

什麼結果也沒有!!換句話說,只要有一個前臺執行緒,不管Main上程式碼是否都已經執行,它也將等待其他前臺執行緒執行完畢才退出.如果Main上的程式碼都已執行同時不存在前臺執行緒,那麼程式自動退出.

同樣還有一個問題存在,我們更改一下上面的程式:

// 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!設定主執行緒為後臺執行緒!  
        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);  
        }  
    }  
}

編譯執行:

D:>csc ThreadDemo.cs

Microsoft (R) Visual C# .NET 編譯器版本 7.10.6001.4

用於 Microsoft (R) .NET Framework 版本 1.1.4322

版權所有 (C) Microsoft Corporation 2001-2002。保留所有權利。

D:>ThreadDemo

the t of thread is Background:False

D:>

問題1:如果按我們剛才的理解,t是前臺執行緒,Main理應等待執行緒t完全執行完畢才是,但是結果卻什麼也沒輸出!這是什麼緣故?暫時還沒研究出答案,待我們深入探討之後在回頭看這個問題

非託管執行緒是通過執行緒ID來標識的,託管執行緒則通過雜湊程式碼(Thread.GetHashCode())或名稱(Thread.Name)來標識.獲取當前執行緒ID採用AppDomain.GetCurrentThreadId().

示例-獲取執行緒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();      
}

編譯執行:

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!如果將main更改為:

#pragma unmanaged

int main()

{

ThreadDelagate *td = new ThreadDelagate;

td->Start();    

}

編譯將得到如下錯誤:

error C3821: “ThreadDelagate” : 託管型別不能用於非託管函式

error C3169: “td” : 在非託管函式內不能宣告託管物件或 __gc 指標

error C3821: “ThreadDelagate” : 託管型別不能用於非託管函式

error C3175: “ThreadDelagate::ThreadDelagate” : 不能從非託管函式“main”呼叫託管型別的方法

error C3821: “td” : 託管型別不能用於非託管函式

error C3175: “ThreadDelagate::Start” : 不能從非託管函式“main”呼叫託管型別的方法

原因我就不多講.很明朗!因此,如果要操縱託管執行緒ID,需先把它儲存起來,然後在非託管程式碼中進行應用.

示例-列舉非託管執行緒(ProcessThread表示作業系統程序執行緒)

// 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);  
        }  
    }  
}

編譯執行:

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

通過列舉的方式我們發現該程式存在7個執行緒,但是在執行初期,我們通過工作管理員發現它的執行緒數才3個!這是什麼原因呢?原來在列舉程序執行緒的操作實際上會使CLR建立更多的執行緒,用以執行此列舉操作!!

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