createthread() 如何更好地释放内存？

Question

I want to close a thread and release memory after createthread() . I did this with return createthread() 's callback and closehandle() . Some people said this can't release memory clear. I am testing it, so far, so good. It looks ok?

I take a flag:endThread to do this, there are too many flags, too many if, it looks ugly, how to make it better?

typedef void(*pfunc)(char*);
HANDLE H_thread=NULL;
int endThread = 0;//0:thread not start;1:end thread order;2:thread started
void mycall(char*s){
    cout << "callback" << endl;
    cout << s << endl;
}
static DWORD WINAPI myfunc(LPVOID lp)
{
    while (1)
    {
        ((pfunc)lp)("2222");
        cout << "thread..........." << endl;
        Sleep(10);
        if (1==endThread)
        {
            endThread = 0;
            return 0;
        }
    }
}
void thread_callback(pfunc call){
    if (0==endThread)
    {
        H_thread = CreateThread(NULL, 0, myfunc, call, 0, NULL);
        endThread = 2;
        call("1111");
    }
}
int _tmain(int argc, _TCHAR* argv[])
{
    while (true)
    {
        thread_callback(mycall);
        endThread = 1;
        //wait for thread end.
        while (endThread != 0){
            Sleep(1);
        }
        CloseHandle(H_thread);
        H_thread = NULL;
    }
    while(1);
    return 0;
}

Answer 1

You are creating and destroying threads over and over. It doesn't even check if the thread was done. It's unlikely that that's your goal. Use WaitForSingleObject or WaitForMultipleObjects to make sure that the thread is done. In a Window program (not console) you can use SendMessage from the thread to GUI thread, to indicate that the thread is done.

Try the example below. Also you can use system("pause"); instead of while(1); , but that's only necessary if you are running the program from VS IDE in debug mode. See also this MSDN example

#include <iostream>
#include <string>
#include <windows.h>

struct T_data {
    std::wstring text;
};

DWORD WINAPI thread_function(void *ptr) {
    T_data* data = (T_data*)ptr;
    MessageBoxW(GetConsoleWindow(), data->text.c_str(), 0, 0);
    return 0;
}

int main() {
    T_data *data = new T_data;
    data->text = L"hello world";
    DWORD threadId;
    HANDLE handle = CreateThread(NULL, 0, thread_function, data, 0, &threadId);

    if (handle) {
        printf("thread started\n");
        while (WaitForSingleObject(handle, 100))
            printf(".");
        printf("\nthread finished\n");
        CloseHandle(handle);
    }

    delete data;
    system("pause");
    return 0;
}

Deleting the data can get tricky if data is shared, depending on where and how you want to do that. The calling thread may delete the data before receiving thread is finished processing it. I'll leave that out since you haven't shown any such shared data in the question.