请高手帮小弟我分析一上这个多线程的小练习程序

2012-11-06

请高手帮我分析一下这个多线程的小练习程序。这个是我按照孙鑫C++视频里面的练习做的我得编程环境是vs2010

请高手帮我分析一下这个多线程的小练习程序。
这个是我按照孙鑫C++视频里面的练习做的我得编程环境是vs2010+win7
代码如下：

C/C++ code

#include<iostream>#include <windows.h>using namespace std;DWORD WINAPI GThreadProc1(    __in  LPVOID lpParameter    );DWORD WINAPI GThreadProc2(    __in  LPVOID lpParameter    );int tickets=100;HANDLE hMutex;int main(){    HANDLE hThread1;    HANDLE hThread2;    hThread1=CreateThread(NULL,0,GThreadProc1,NULL,0,NULL);    hThread2=CreateThread(NULL,0,GThreadProc2,NULL,0,NULL);        Sleep(5000);    hMutex=CreateMutex(NULL,false,NULL);    return 0;}DWORD WINAPI GThreadProc1(    __in  LPVOID lpParameter    ){        WaitForSingleObject(hMutex,INFINITE);    while (true)    {        Sleep(1);        if (tickets>0)        {            cout<<"No.1 seller sells ticket :"<<tickets--<<endl;        }        ReleaseMutex(hMutex);    }    return 0;}DWORD WINAPI GThreadProc2(    __in  LPVOID lpParameter    ){        WaitForSingleObject(hMutex,INFINITE);    while (true)    {        Sleep(1);        if (tickets>0)        {            cout<<"No.2 seller sells ticket :"<<tickets--<<endl;            ReleaseMutex(hMutex);        }    }    return 0;}

为什么会出现如下图所示的运行结果：

如果我把代码中两个线程的sleep(1)去掉又会出现如下两图所示的情况
1

2

我的理想状况是让他们按照顺序卖票。请问出现以上情况的原理原因是什么啊？希望高手多多帮助。

[解决办法]
多线程互斥量

sleep在互斥量的保护范围之内

不知道你是否是把两个sleep同时去除的呢？？
[解决办法]
#include<iostream>
#include <windows.h>
using namespace std;

DWORD WINAPI GThreadProc1(
__in LPVOID lpParameter
);

DWORD WINAPI GThreadProc2(
__in LPVOID lpParameter
);

int tickets=100;
HANDLE hMutex;
int main()
{
HANDLE hThread1;
HANDLE hThread2;

hMutex=CreateMutex(NULL,false,NULL);

hThread1=CreateThread(NULL,0,GThreadProc1,NULL,0,NULL);
hThread2=CreateThread(NULL,0,GThreadProc2,NULL,0,NULL);

Sleep(5000);

system("pause");

return 0;
}
DWORD WINAPI GThreadProc1(
__in LPVOID lpParameter
)
{

while (true)
{
WaitForSingleObject(hMutex,INFINITE);
if (tickets>0)
{
cout<<"No.1 seller sells ticket :"<<tickets--<<endl;
}
else
{
break;
}
ReleaseMutex(hMutex);
}
return 0;
}

DWORD WINAPI GThreadProc2(
__in LPVOID lpParameter
)
{

while (true)
{
WaitForSingleObject(hMutex,INFINITE);
if (tickets>0)
{
cout<<"No.2 seller sells ticket :"<<tickets--<<endl;
ReleaseMutex(hMutex);
}
else
{
break;
}
}
return 0;
}

[解决办法]
你线程2的ReleaseMutex(hMutex)语句写错了吧;
怎么写到if语句里面啊。。要是不满足条件，。。。那不是就执行不了ReleaseMutex(hMutex);
所以会出现那种情况

[解决办法]
上面没贴好

C/C++ code

#include<iostream>#include <windows.h>using namespace std;DWORD WINAPI GThreadProc1(    LPVOID lpParameter    );DWORD WINAPI GThreadProc2(    LPVOID lpParameter    );int tickets=100;//HANDLE hMutex;CRITICAL_SECTION g_cs;int main(){    HANDLE hThread1;    HANDLE hThread2;        InitializeCriticalSection(&g_cs);    //hMutex=CreateMutex(NULL,false,NULL);    hThread1=CreateThread(NULL,0,GThreadProc1,NULL,0,NULL);    hThread2=CreateThread(NULL,0,GThreadProc2,NULL,0,NULL);    Sleep(5000);    CloseHandle(hThread1);    CloseHandle(hThread2);    DeleteCriticalSection(&g_cs);    return 0;}DWORD WINAPI GThreadProc1(      LPVOID lpParameter    ){        //WaitForSingleObject(hMutex,INFINITE);    while (true)    {        ::EnterCriticalSection(&g_cs);        Sleep(1);        if (tickets>0)        {            cout<<"No.1 seller sells ticket :"<<tickets--<<endl;        }        ::LeaveCriticalSection(&g_cs);        //ReleaseMutex(hMutex);    }    return 0;}DWORD WINAPI GThreadProc2(      LPVOID lpParameter    ){        //WaitForSingleObject(hMutex,INFINITE);    while (true)    {        ::EnterCriticalSection(&g_cs);        Sleep(1);        if (tickets>0)        {            cout<<"No.2 seller sells ticket :"<<tickets--<<endl;            //ReleaseMutex(hMutex);        }        ::LeaveCriticalSection(&g_cs);    }    return 0;}

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