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  • C/C++

      前几天简单对C和C++中的创建多线程的函数进行了测试,这篇随笔就简单介绍一下创建线程的相关函数。

      C中三个创建线程函数:pthread_create()、_beginthread()、CreateThread()

      三个关闭线程函数:pthread_exit()、_endthread()、ExitThread()

      头文件分别是:pthread.h、process.h、processthreadsapi.h

      pthread_create()函数原型:

    int pthread_create(pthread_t *tidp,
    const pthread_attr_t *attr,
    (void*)(*start_rtn)(void*),
    void *arg);

      _beginthread()函数原型:

    uintptr_t _beginthread(void( *start_address )( void * ),
    unsignedstack_size,void *arglist);

      _beginthread()函数是调用CreateThread()函数来实现的,但多了一些功能,是C标准库中提供的函数。而CreateThread()函数创建一个线程在调用进程的虚拟地址空间内执行,是操作系统中的函数。可参考解释:http://bbs.csdn.net/topics/21693。

      CreateThread()函数原型:

    HANDLE WINAPI CreateThread(
      _In_opt_  LPSECURITY_ATTRIBUTES  lpThreadAttributes,
      _In_      SIZE_T                 dwStackSize,
      _In_      LPTHREAD_START_ROUTINE lpStartAddress,
      _In_opt_  LPVOID                 lpParameter,
      _In_      DWORD                  dwCreationFlags,
      _Out_opt_ LPDWORD                lpThreadId
    );
    

      pthread_exit()函数原型:

    void pthread_exit(void *retval);

      _endthread()函数原型:

    void _endthread( void );  
    void _endthreadex(   
       unsigned retval   
    );  

      ExitThread()函数原型:

    VOID WINAPI ExitThread(
      _In_ DWORD dwExitCode
    );
    

      貌似要使用pthread_exit();需要安全释放,否则会出现内存泄露:pthread_exit()

      下面测试一下各个函数:

      pthread.h:

    #include <stdio.h>
    #include <stdlib.h>
    #include <pthread.h>
    
    #define MAXTHREADS 5
    
    void* Run(void* args)
    {
        printf("%d:Hello World!
    ", *((int*)args));
        pthread_exit(NULL);
        return NULL;
    }
    
    int main()
    {
        pthread_t tid[MAXTHREADS];
        pthread_attr_t attr;
        void*status;
        int ret;
    
        pthread_attr_init(&attr);//初始化attr
        pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_JOINABLE);//设置获得attr的线程为可连接的:PTHREAD_CREATE_JOINABLE 原型为 0
    
        for(int i = 0; i < MAXTHREADS; i++)
        {
            if((ret = pthread_create(&tid[i], &attr, Run, (void*)&i)) != 0)//获得attr,则线程可连接
            {
                puts("Pthread_Create error!");
                exit(1);
            }
            pthread_join(tid[i], &status);//等待线程结束,结束的线程便不能再被连接
        }
    
        pthread_attr_destroy(&attr);//销毁attr资源
    
        return 0;
    }

      pthread_join等待其他线程结束后再连接能连接的函数,已经结束的线程便不能再被连接。所以输出结果可看到是按顺序执行的。感觉就是加上了互斥锁,不知道理解对不对?

      process.h:

    #include <stdio.h>
    #include <stdlib.h>
    #include <process.h>
    
    #define MAXTHREAD 5
    
    void run(void*i)
    {
        printf("%d:Hello world!
    ", *((int*)i));
    }
    
    int main()
    {
        for(int i = 0; i < MAXTHREAD; i++) {
            _beginthread(&run, 0, (void*)&i);
        }
        _endthread();
    
        return 0;
    }

      消除了类型强转的警告,但程序无法正常退出,有时也无法正常进行。

    --------------------update 2018-02-24 16:09:01---------------------

      processthreadsapi.h:

    #include <windows.h>
    
    #define MAXTHREAD 5
    
    HANDLE ghMutex;
    
    DWORD WINAPI Run_Process(LPVOID p) {
    
        WaitForSingleObject(ghMutex, INFINITE);
        try
        {
            TCHAR s = *((int*)p)+'0';
            MessageBoxA(NULL, TEXT("Hello world!"), TEXT(&s), MB_ICONWARNING | MB_OK);
            ReleaseMutex(ghMutex);
        }
        catch(...)
        {
            if (! ReleaseMutex(ghMutex))
                MessageBoxA(NULL, TEXT("ReleaseMutex Error!"), TEXT("ERROR"), MB_ICONERROR | MB_OK);
        }
    
        return GetLastError();
    }
    
    int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE HPrevInstance, PSTR szCmdLine, int iCmdShow)
    {
        DWORD   dwThreadIdArray[MAXTHREAD];
        HANDLE  hThreadArray[MAXTHREAD];
    
        if((ghMutex = CreateMutex(NULL, FALSE, NULL)) == NULL)
        {
            ExitProcess(1);
        }
    
    	for(int i = 0; i < MAXTHREAD; i++) {
            hThreadArray[i] = CreateThread(
               NULL,
               0,
               Run_Process,
               (LPVOID)&i,
               0,
               &dwThreadIdArray[i]);
    
            if (hThreadArray[i] == NULL)
            {
               ExitProcess(3);
            }
    	}
    
    	WaitForMultipleObjects(MAXTHREAD, hThreadArray, TRUE, INFINITE);
    
    	for(int i = 0; i < MAXTHREAD; i++)
        {
            CloseHandle(hThreadArray[i]);
        }
    
        CloseHandle(ghMutex);
    
    	return 0;
    }

      参考我的这篇随笔:

    http://www.cnblogs.com/darkchii/p/8447863.html

    -------------------------------

      参考资料:

    http://www.man7.org/linux/man-pages/man3/pthread_exit.3.html
    http://www.man7.org/linux/man-pages/man3/pthread_create.3.html
    http://www.cppblog.com/prayer/archive/2012/04/23/172427.html
    https://msdn.microsoft.com/en-us/library/windows/desktop/ms682659(v=vs.85).aspx
    https://msdn.microsoft.com/en-us/library/windows/desktop/ms682453(v=vs.85).aspx
    https://msdn.microsoft.com/zh-cn/library/hw264s73.aspx
    

      

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  • 原文地址:https://www.cnblogs.com/darkchii/p/8137530.html
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