C++多线程（一）
WIN 多线程API
一 简单实例
比较简单的代码，创建10个线程，其中使第4个线程在一创建就挂起，等到其他的线程执行的差不多的时候再使第4个线程恢复执行。
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>
#define THREAD_NUM 10
DWORD WINAPI PrintThreads (LPVOID);
int main ()
{
HANDLE hThread[THREAD_NUM];
DWORD dwThreadID[THREAD_NUM];
for (int i=0; i<THREAD_NUM; ++i)
{
int isStartImmediate = 0;
if(3 == i)
isStartImmediate = CREATE_SUSPENDED;
hThread[i]=CreateThread(NULL, // security attributes that should be applied to the new thread,
// this is for NT. Use NULL to get the default security attributes. Use NULL for win95
0, // default size of 1MB can be passed by passing zero.
PrintThreads, // function name:address of the function where the new thread starts.
(LPVOID)i, // parameter(void pointer): pointer to the 32 bit parameter that will be passed into the thread
isStartImmediate, // flags to control the creation of the thread. Passing zero starts the thread immediately.
// Passing CREATE_SUSPENDED suspends the thread until the ResumeThread( ) function is called.
&dwThreadID[i] // pointer to a 32-bit variable that receives the thread identifier.
);
if (hThread[i])
{
printf ("Thread launched successfully/n");
}
}
printf("Start sleep 100, and let other thread excute/n");
Sleep (100);
printf("Start sleep 100, and thread 3 excute/n");
ResumeThread(hThread[3]);
Sleep(100);
for(int i = 0; i<THREAD_NUM; ++i)
{
if (hThread[i])
{
CloseHandle(hThread[i]); // You need to use this to release kernel objects when you are done using them.
// If a process exits without closing the thread handle,
// the operating system drops the reference counts for those objects.
// But if a process frequently creates threads without closing the handles,
// there could be hundreds of thread kernel objects lying around and these resource leaks can have a big hit on performance.
}
}
return (0);
}
//function PrintThreads
DWORD WINAPI PrintThreads (LPVOID num)
{
for (int i=0; i<10; i++)
printf ("Thread Number is %d%d%d/n", num,num,num);
return 0;
}
一 简单实例
比较简单的代码，创建10个线程，其中使第4个线程在一创建就挂起，等到其他的线程执行的差不多的时候再使第4个线程恢复执行。
#include <stdio.h> #include <stdlib.h> #include <windows.h> #define THREAD_NUM 10DWORD WINAPI PrintThreads (LPVOID);int main () { HANDLE hThread[THREAD_NUM]; DWORD dwThreadID[THREAD_NUM]; for (int i=0; i<THREAD_NUM; ++i) { int isStartImmediate = 0; if(3 == i) isStartImmediate = CREATE_SUSPENDED; hThread[i]=CreateThread(NULL, // security attributes that should be applied to the new thread, // this is for NT. Use NULL to get the default security attributes. Use NULL for win95 0, // default size of 1MB can be passed by passing zero. PrintThreads, // function name:address of the function where the new thread starts. (LPVOID)i, // parameter(void pointer): pointer to the 32 bit parameter that will be passed into the thread isStartImmediate, // flags to control the creation of the thread. Passing zero starts the thread immediately. // Passing CREATE_SUSPENDED suspends the thread until the ResumeThread( ) function is called. &dwThreadID[i] // pointer to a 32-bit variable that receives the thread identifier. ); if (hThread[i]) { printf ("Thread launched successfully/n"); } } printf("Start sleep 100, and let other thread excute/n"); Sleep (100); printf("Start sleep 100, and thread 3 excute/n"); ResumeThread(hThread[3]); Sleep(100); for(int i = 0; i<THREAD_NUM; ++i) { if (hThread[i]) { CloseHandle(hThread[i]); // You need to use this to release kernel objects when you are done using them. // If a process exits without closing the thread handle, // the operating system drops the reference counts for those objects. // But if a process frequently creates threads without closing the handles, // there could be hundreds of thread kernel objects lying around and these resource leaks can have a big hit on performance. } } return (0); } //function PrintThreads DWORD WINAPI PrintThreads (LPVOID num){ for (int i=0; i<10; i++) printf ("Thread Number is %d%d%d/n", num,num,num); return 0;}
二 其他基本API的说明
CreateThread() 调用成功返回句柄和一个id。
CloseHandle() 关闭一个打开的对象句柄，该对象句柄可以是线程句柄，也可以是进程、信号量等其他内核对象的句柄.
SuspendThread(HANDLE) 允许开发人员将HANDLE指定的线程挂起，如果要挂起的线程占有共享资源，则可能导致死锁。
ResumeThread(HANDLE) 恢复指定的线程。
TerminateThread() 立即终止线程的工作，不做任何清理工作。
ExitThread() 线程函数返回时回调用次函数，所以一般我们不去显示的调用。
ExitThread是推荐使用的结束一个线程的方法，当调用该函数时，当前线程的栈被释放，然后线程终止，相对于TerminateThread函数来说，这样做能够更好地完成附加在该线程上的DLL的清除工作. 但是ExitThread()会导致线程在清处构造器/自动变量之前就终止，所以我们最好不要显示的调用ExitThread()。
