为什么下面的代码示例会导致一个线程执行的方式比另一个更多,但互斥体不会呢?Windows 7中的关键部分问题
#include <windows.h>
#include <conio.h>
#include <process.h>
#include <iostream>
using namespace std;
typedef struct _THREAD_INFO_ {
COORD coord; // a structure containing x and y coordinates
INT threadNumber; // each thread has it's own number
INT count;
}THREAD_INFO, * PTHREAD_INFO;
void gotoxy(int x, int y);
BOOL g_bRun;
CRITICAL_SECTION g_cs;
unsigned __stdcall ThreadFunc(void* pArguments)
{
PTHREAD_INFO info = (PTHREAD_INFO)pArguments;
while(g_bRun)
{
EnterCriticalSection(&g_cs);
//if(TryEnterCriticalSection(&g_cs))
//{
gotoxy(info->coord.X, info->coord.Y);
cout << "T" << info->threadNumber << ": " << info->count;
info->count++;
LeaveCriticalSection(&g_cs);
//}
}
ExitThread(0);
return 0;
}
int main(void)
{
// OR unsigned int
unsigned int id0, id1; // a place to store the thread ID returned from CreateThread
HANDLE h0, h1; // handles to theads
THREAD_INFO tInfo[2]; // only one of these - not optimal!
g_bRun = TRUE;
ZeroMemory(&tInfo, sizeof(tInfo)); // win32 function - memset(&buffer, 0, sizeof(buffer))
InitializeCriticalSection(&g_cs);
// setup data for the first thread
tInfo[0].threadNumber = 1;
tInfo[0].coord.X = 0;
tInfo[0].coord.Y = 0;
h0 = (HANDLE)_beginthreadex(
NULL, // no security attributes
0, // defaut stack size
&ThreadFunc, // pointer to function
&tInfo[0], // each thread gets its own data to output
0, // 0 for running or CREATE_SUSPENDED
&id0); // return thread id - reused here
// setup data for the second thread
tInfo[1].threadNumber = 2;
tInfo[1].coord.X = 15;
tInfo[1].coord.Y = 0;
h1 = (HANDLE)_beginthreadex(
NULL, // no security attributes
0, // defaut stack size
&ThreadFunc, // pointer to function
&tInfo[1], // each thread gets its own data to output
0, // 0 for running or CREATE_SUSPENDED
&id1); // return thread id - reused here
_getch();
g_bRun = FALSE;
return 0;
}
void gotoxy(int x, int y) // x=column position and y=row position
{
HANDLE hdl;
COORD coords;
hdl = GetStdHandle(STD_OUTPUT_HANDLE);
coords.X = x;
coords.Y = y;
SetConsoleCursorPosition(hdl, coords);
}
由于开关。论坛帖子似乎回答了这个问题。结论似乎是,关键部分不是共享资源(如日志文件等)的好方法。 – user483504 2010-10-22 00:02:45
这不是一个正确的结论。关键部分应该非常好。只要磁盘带宽高于日志文件写入速率,所有线程最终都将被服务。当写入总速率超过磁盘带宽时,您遇到的问题比不公平的调度更大。 – MSalters 2010-10-22 10:37:50