C/C++ 创建线程解析
2013-12-16 19:52
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_beginThreadex创建多线程解读
需要的设置:ProjectàSetting-->C/C++-->User run-time library 选择Debug Multithreaded 或者Multithreaded。即使用: MT或MTD。
源码如下:
[cpp] view plaincopyprint? #include <stdio.h>
#include <string> // for STL string class
#include <windows.h> // for HANDLE
#include <process.h> // for _beginthread()
using namespace std;
class ThreadX
{
private:
int loopStart;
int loopEnd;
int dispFrequency;
public:
string threadName;
ThreadX( int startValue, int endValue, int frequency )
{
loopStart = startValue;
loopEnd = endValue;
dispFrequency = frequency;
}
static unsigned __stdcall ThreadStaticEntryPoint(void * pThis)
{
ThreadX * pthX = (ThreadX*)pThis; // the tricky cast
pthX->ThreadEntryPoint(); // now call the true entry-point-function
return 1; // the thread exit code
}
void ThreadEntryPoint()
{
for (int i = loopStart; i <= loopEnd; ++i)
{
if (i % dispFrequency == 0)
{
printf( "%s: i = %d\n", threadName.c_str(), i );
}
}
printf( "%s thread terminating\n", threadName.c_str() );
}
};
int main()
{
ThreadX * o1 = new ThreadX( 0, 1, 2000 );
HANDLE hth1;
unsigned uiThread1ID;
hth1 = (HANDLE)_beginthreadex( NULL, // security
0, // stack size
ThreadX::ThreadStaticEntryPoint,
o1, // arg list
CREATE_SUSPENDED, // so we can later call ResumeThread()
&uiThread1ID );
if ( hth1 == 0 )
printf("Failed to create thread 1\n");
DWORD dwExitCode;
GetExitCodeThread( hth1, &dwExitCode ); // should be STILL_ACTIVE = 0x00000103 = 259
printf( "initial thread 1 exit code = %u\n", dwExitCode );
o1->threadName = "t1";
ThreadX * o2 = new ThreadX( -100000, 0, 2000 );
HANDLE hth2;
unsigned uiThread2ID;
hth2 = (HANDLE)_beginthreadex( NULL, // security
0, // stack size
ThreadX::ThreadStaticEntryPoint,
o2, // arg list
CREATE_SUSPENDED, // so we can later call ResumeThread()
&uiThread2ID );
if ( hth2 == 0 )
printf("Failed to create thread 2\n");
GetExitCodeThread( hth2, &dwExitCode ); // should be STILL_ACTIVE = 0x00000103 = 259
printf( "initial thread 2 exit code = %u\n", dwExitCode );
o2->threadName = "t2";
ResumeThread( hth1 ); // serves the purpose of Jaeschke's t1->Start()
ResumeThread( hth2 );
WaitForSingleObject( hth1, INFINITE );
WaitForSingleObject( hth2, INFINITE );
GetExitCodeThread( hth1, &dwExitCode );
printf( "thread 1 exited with code %u\n", dwExitCode );
GetExitCodeThread( hth2, &dwExitCode );
printf( "thread 2 exited with code %u\n", dwExitCode );
CloseHandle( hth1 );
CloseHandle( hth2 );
delete o1;
o1 = NULL;
delete o2;
o2 = NULL;
printf("Primary thread terminating.\n");
return 0;
}
二、解释
(1)如果你正在编写C/C++代码,决不应该调用CreateThread。相反,应该使用VisualC++运行期库函数_beginthreadex,退出也应该使用_endthreadex。如果不使用Microsoft的VisualC++编译器,你的编译器供应商有它自己的CreateThread替代函数。不管这个替代函数是什么,你都必须使用。 (2)因为_beginthreadex和_endthreadex是CRT线程函数,所以必须注意编译选项runtimelibaray的选择,使用MT或MTD。[MultiThreaded , Debug MultiThreaded]。 (3)_beginthreadex函数的参数列表与CreateThread函数的参数列表是相同的,但是参数名和类型并不完全相同。这是因为Microsoft的C/C++运行期库的开发小组认为,C/C++运行期函数不应该对Windows数据类型有任何依赖。_beginthreadex函数也像CreateThread那样,返回新创建的线程的句柄。 下面是关于_beginthreadex的一些要点: 1)每个线程均获得由C/C++运行期库的堆栈分配的自己的tiddata内存结构。(tiddata结构位于Mtdll.h文件中的VisualC++源代码中)。 2)传递给_beginthreadex的线程函数的地址保存在tiddata内存块中。传递给该函数的参数也保存在该数据块中。 3)_beginthreadex确实从内部调用CreateThread,因为这是操作系统了解如何创建新线程的唯一方法。 4)当调用CreatetThread时,它被告知通过调用_threadstartex而不是pfnStartAddr来启动执行新线程。还有,传递给线程函数的参数是tiddata结构而不是pvParam的地址。 5)如果一切顺利,就会像CreateThread那样返回线程句柄。如果任何操作失败了,便返回NULL。 (4)_endthreadex的一些要点: C运行期库的_getptd函数内部调用操作系统的TlsGetValue函数,该函数负责检索调用线程的tiddata内存块的地址。 然后该数据块被释放,而操作系统的ExitThread函数被调用,以便真正撤消该线程。当然,退出代码要正确地设置和传递。 (5)虽然也提供了简化版的的_beginthread和_endthread,但是可控制性太差,所以一般不使用。 (6)线程handle因为是内核对象,所以需要在最后closehandle。 (7)更多的API: HANDLE GetCurrentProcess(); HANDLE GetCurrentThread(); DWORD GetCurrentProcessId(); DWORD GetCurrentThreadId()。 DWORD SetThreadIdealProcessor(HANDLE hThread,DWORDdwIdealProcessor); BOOL SetThreadPriority(HANDLE hThread,int nPriority); BOOL SetPriorityClass(GetCurrentProcess(), IDLE_PRIORITY_CLASS); BOOL GetThreadContext(HANDLE hThread,PCONTEXTpContext); BOOL SwitchToThread();
一、需要的头文件支持
#include <process.h> // for _beginthread()需要的设置:ProjectàSetting-->C/C++-->User run-time library 选择Debug Multithreaded 或者Multithreaded。即使用: MT或MTD。
源码如下:
[cpp] view plaincopyprint? #include <stdio.h>
#include <string> // for STL string class
#include <windows.h> // for HANDLE
#include <process.h> // for _beginthread()
using namespace std;
class ThreadX
{
private:
int loopStart;
int loopEnd;
int dispFrequency;
public:
string threadName;
ThreadX( int startValue, int endValue, int frequency )
{
loopStart = startValue;
loopEnd = endValue;
dispFrequency = frequency;
}
static unsigned __stdcall ThreadStaticEntryPoint(void * pThis)
{
ThreadX * pthX = (ThreadX*)pThis; // the tricky cast
pthX->ThreadEntryPoint(); // now call the true entry-point-function
return 1; // the thread exit code
}
void ThreadEntryPoint()
{
for (int i = loopStart; i <= loopEnd; ++i)
{
if (i % dispFrequency == 0)
{
printf( "%s: i = %d\n", threadName.c_str(), i );
}
}
printf( "%s thread terminating\n", threadName.c_str() );
}
};
int main()
{
ThreadX * o1 = new ThreadX( 0, 1, 2000 );
HANDLE hth1;
unsigned uiThread1ID;
hth1 = (HANDLE)_beginthreadex( NULL, // security
0, // stack size
ThreadX::ThreadStaticEntryPoint,
o1, // arg list
CREATE_SUSPENDED, // so we can later call ResumeThread()
&uiThread1ID );
if ( hth1 == 0 )
printf("Failed to create thread 1\n");
DWORD dwExitCode;
GetExitCodeThread( hth1, &dwExitCode ); // should be STILL_ACTIVE = 0x00000103 = 259
printf( "initial thread 1 exit code = %u\n", dwExitCode );
o1->threadName = "t1";
ThreadX * o2 = new ThreadX( -100000, 0, 2000 );
HANDLE hth2;
unsigned uiThread2ID;
hth2 = (HANDLE)_beginthreadex( NULL, // security
0, // stack size
ThreadX::ThreadStaticEntryPoint,
o2, // arg list
CREATE_SUSPENDED, // so we can later call ResumeThread()
&uiThread2ID );
if ( hth2 == 0 )
printf("Failed to create thread 2\n");
GetExitCodeThread( hth2, &dwExitCode ); // should be STILL_ACTIVE = 0x00000103 = 259
printf( "initial thread 2 exit code = %u\n", dwExitCode );
o2->threadName = "t2";
ResumeThread( hth1 ); // serves the purpose of Jaeschke's t1->Start()
ResumeThread( hth2 );
WaitForSingleObject( hth1, INFINITE );
WaitForSingleObject( hth2, INFINITE );
GetExitCodeThread( hth1, &dwExitCode );
printf( "thread 1 exited with code %u\n", dwExitCode );
GetExitCodeThread( hth2, &dwExitCode );
printf( "thread 2 exited with code %u\n", dwExitCode );
CloseHandle( hth1 );
CloseHandle( hth2 );
delete o1;
o1 = NULL;
delete o2;
o2 = NULL;
printf("Primary thread terminating.\n");
return 0;
}
#include <stdio.h> #include <string> // for STL string class #include <windows.h> // for HANDLE #include <process.h> // for _beginthread() using namespace std; class ThreadX { private: int loopStart; int loopEnd; int dispFrequency; public: string threadName; ThreadX( int startValue, int endValue, int frequency ) { loopStart = startValue; loopEnd = endValue; dispFrequency = frequency; } static unsigned __stdcall ThreadStaticEntryPoint(void * pThis) { ThreadX * pthX = (ThreadX*)pThis; // the tricky cast pthX->ThreadEntryPoint(); // now call the true entry-point-function return 1; // the thread exit code } void ThreadEntryPoint() { for (int i = loopStart; i <= loopEnd; ++i) { if (i % dispFrequency == 0) { printf( "%s: i = %d\n", threadName.c_str(), i ); } } printf( "%s thread terminating\n", threadName.c_str() ); } }; int main() { ThreadX * o1 = new ThreadX( 0, 1, 2000 ); HANDLE hth1; unsigned uiThread1ID; hth1 = (HANDLE)_beginthreadex( NULL, // security 0, // stack size ThreadX::ThreadStaticEntryPoint, o1, // arg list CREATE_SUSPENDED, // so we can later call ResumeThread() &uiThread1ID ); if ( hth1 == 0 ) printf("Failed to create thread 1\n"); DWORD dwExitCode; GetExitCodeThread( hth1, &dwExitCode ); // should be STILL_ACTIVE = 0x00000103 = 259 printf( "initial thread 1 exit code = %u\n", dwExitCode ); o1->threadName = "t1"; ThreadX * o2 = new ThreadX( -100000, 0, 2000 ); HANDLE hth2; unsigned uiThread2ID; hth2 = (HANDLE)_beginthreadex( NULL, // security 0, // stack size ThreadX::ThreadStaticEntryPoint, o2, // arg list CREATE_SUSPENDED, // so we can later call ResumeThread() &uiThread2ID ); if ( hth2 == 0 ) printf("Failed to create thread 2\n"); GetExitCodeThread( hth2, &dwExitCode ); // should be STILL_ACTIVE = 0x00000103 = 259 printf( "initial thread 2 exit code = %u\n", dwExitCode ); o2->threadName = "t2"; ResumeThread( hth1 ); // serves the purpose of Jaeschke's t1->Start() ResumeThread( hth2 ); WaitForSingleObject( hth1, INFINITE ); WaitForSingleObject( hth2, INFINITE ); GetExitCodeThread( hth1, &dwExitCode ); printf( "thread 1 exited with code %u\n", dwExitCode ); GetExitCodeThread( hth2, &dwExitCode ); printf( "thread 2 exited with code %u\n", dwExitCode ); CloseHandle( hth1 ); CloseHandle( hth2 ); delete o1; o1 = NULL; delete o2; o2 = NULL; printf("Primary thread terminating.\n"); return 0; }
二、解释
(1)如果你正在编写C/C++代码,决不应该调用CreateThread。相反,应该使用VisualC++运行期库函数_beginthreadex,退出也应该使用_endthreadex。如果不使用Microsoft的VisualC++编译器,你的编译器供应商有它自己的CreateThread替代函数。不管这个替代函数是什么,你都必须使用。 (2)因为_beginthreadex和_endthreadex是CRT线程函数,所以必须注意编译选项runtimelibaray的选择,使用MT或MTD。[MultiThreaded , Debug MultiThreaded]。 (3)_beginthreadex函数的参数列表与CreateThread函数的参数列表是相同的,但是参数名和类型并不完全相同。这是因为Microsoft的C/C++运行期库的开发小组认为,C/C++运行期函数不应该对Windows数据类型有任何依赖。_beginthreadex函数也像CreateThread那样,返回新创建的线程的句柄。 下面是关于_beginthreadex的一些要点: 1)每个线程均获得由C/C++运行期库的堆栈分配的自己的tiddata内存结构。(tiddata结构位于Mtdll.h文件中的VisualC++源代码中)。 2)传递给_beginthreadex的线程函数的地址保存在tiddata内存块中。传递给该函数的参数也保存在该数据块中。 3)_beginthreadex确实从内部调用CreateThread,因为这是操作系统了解如何创建新线程的唯一方法。 4)当调用CreatetThread时,它被告知通过调用_threadstartex而不是pfnStartAddr来启动执行新线程。还有,传递给线程函数的参数是tiddata结构而不是pvParam的地址。 5)如果一切顺利,就会像CreateThread那样返回线程句柄。如果任何操作失败了,便返回NULL。 (4)_endthreadex的一些要点: C运行期库的_getptd函数内部调用操作系统的TlsGetValue函数,该函数负责检索调用线程的tiddata内存块的地址。 然后该数据块被释放,而操作系统的ExitThread函数被调用,以便真正撤消该线程。当然,退出代码要正确地设置和传递。 (5)虽然也提供了简化版的的_beginthread和_endthread,但是可控制性太差,所以一般不使用。 (6)线程handle因为是内核对象,所以需要在最后closehandle。 (7)更多的API: HANDLE GetCurrentProcess(); HANDLE GetCurrentThread(); DWORD GetCurrentProcessId(); DWORD GetCurrentThreadId()。 DWORD SetThreadIdealProcessor(HANDLE hThread,DWORDdwIdealProcessor); BOOL SetThreadPriority(HANDLE hThread,int nPriority); BOOL SetPriorityClass(GetCurrentProcess(), IDLE_PRIORITY_CLASS); BOOL GetThreadContext(HANDLE hThread,PCONTEXTpContext); BOOL SwitchToThread();
三、注意
(1)C++主线程的终止,同时也会终止所有主线程创建的子线程,不管子线程有没有执行完毕。所以上面的代码中如果不调用WaitForSingleObject,则2个子线程t1和t2可能并没有执行完毕或根本没有执行。 (2)如果某线程挂起,然后有调用WaitForSingleObject等待该线程,就会导致死锁。所以上面的代码如果不调用resumethread,则会死锁。四、为什么用_beginthreadex而不是CreateThread?
为什么要用C运行时库的_beginthreadex代替操作系统的CreateThread来创建线程? 来源自自1999年7月MSJ杂志的《Win32 Q&A》栏目 你也许会说我一直用CreateThread来创建线程,一直都工作得好好的,为什么要用_beginthreadex来代替CreateThread,下面让我来告诉你为什么。 回答一个问题可以有两种方式,一种是简单的,一种是复杂的。 如果你不愿意看下面的长篇大论,那我可以告诉你简单的答案:_beginthreadex在内部调用了CreateThread,在调用之前_beginthreadex做了很多的工作,从而使得它比CreateThread更安全。相关文章推荐
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