Different threading in Visual C++

I do not understand what is the difference between using

Code:

 
CWinThread* AfxBeginThread(
   AFX_THREADPROC pfnThreadProc,
   LPVOID pParam,
   int nPriority = THREAD_PRIORITY_NORMAL,
   UINT nStackSize = 0,
   DWORD dwCreateFlags = 0,
   LPSECURITY_ATTRIBUTES lpSecurityAttrs = NULL 
);
CWinThread* AfxBeginThread(
   CRuntimeClass* pThreadClass,
   int nPriority = THREAD_PRIORITY_NORMAL,
   UINT nStackSize = 0,
   DWORD dwCreateFlags = 0,
   LPSECURITY_ATTRIBUTES lpSecurityAttrs = NULL 
);

or instead using

Code:

HANDLE WINAPI CreateThread(
  __in_opt   LPSECURITY_ATTRIBUTES lpThreadAttributes,
  __in       SIZE_T dwStackSize,
  __in       LPTHREAD_START_ROUTINE lpStartAddress,
  __in_opt   LPVOID lpParameter,
  __in       DWORD dwCreationFlags,
  __out_opt  LPDWORD lpThreadId
);

in Windows XP or Windows CE

What is the difference in practice (except for the first using an object and the second only an handle)? Are they compliant one another may be the first an enhacement of the second??

Are they both used together with the same following function to test thread exit?

Code:

BOOL WINAPI GetExitCodeThread(
  __in   HANDLE hThread,
  __out  LPDWORD lpExitCode
);

Thank you

>> what is the difference
AfxBeginThread is part of the MFC framework/library. If you use threading in an MFC application/dll, and that thread uses any other MFC objects/functions, then you should use AfxBeginThread.

AfxBeginThread uses _beginthreadex. This is the CRT's thread creation API. If your thread uses any of CRT fucntions, then it should use _beginthreadex to avoid certain types of memory leaks.

CreateThread is the OS interface for thread creation in user mode applications. So you have AfxBeginThread -> _beginthreadex -> CreateThread.

For each of the interfaces, you can get the thread handle for use in Win32 API functions. With the MFC interfaces, using the raw handle safely is a little more tricky as there are some rules that need to be followed.

gg

Originally Posted by Codeplug

>> what is the difference
AfxBeginThread is part of the MFC framework/library. If you use threading in an MFC application/dll, and that thread uses any other MFC objects/functions, then you should use AfxBeginThread.

AfxBeginThread uses _beginthreadex. This is the CRT's thread creation API. If your thread uses any of CRT fucntions, then it should use _beginthreadex to avoid certain types of memory leaks.

CreateThread is the OS interface for thread creation in user mode applications. So you have AfxBeginThread -> _beginthreadex -> CreateThread.

For each of the interfaces, you can get the thread handle for use in Win32 API functions. With the MFC interfaces, using the raw handle safely is a little more tricky as there are some rules that need to be followed.

gg

It is quite more complicated than pthreading
I had a look to msdn but docs there are very "disperse" One must read here and there and it's hard to have a good understanding of the subject
Are there some tutorials / example codes you would suggest?

If I use AfxBeginThread or Createthread I can use in both cases GetExitCodeThread?
is it compulsory to do it (like in pthread with pthread_join() ) ?

GetExitCodeThread() is indeed the way to get the exit code of a thread (or "not yet exited" in relevant cases).

As to which variant of thread you should use, it depends quite a bit on what you are actually doing within the thread.

If you are using MFC, then AfxThread... is the right interface to use.

If you are not using MFC, then _beginthread() is probably the right thing to do, unless you really do not want to call any C library functions in the thread. CreateThread() is the OS-level function that creates a thread.

--
Mats

I really have to try this multithreading lark sometime.

Originally Posted by matsp

GetExitCodeThread() is indeed the way to get the exit code of a thread (or "not yet exited" in relevant cases).

As to which variant of thread you should use, it depends quite a bit on what you are actually doing within the thread.

If you are using MFC, then AfxThread... is the right interface to use.

If you are not using MFC, then _beginthread() is probably the right thing to do, unless you really do not want to call any C library functions in the thread. CreateThread() is the OS-level function that creates a thread.

--
Mats

I worked on a project done by others and modified by me, using CreateThread and also C lib funcs and I noticed no problem (on W CE 4.2 with embedded Visual C ++ 4.2)

Originally Posted by mynickmynick

I worked on a project done by others and modified by me, using CreateThread and also C lib funcs and I noticed no problem (on W CE 4.2 with embedded Visual C ++ 4.2)

"Noticing no problem" when crossing the road against a red-light is also possible, right? The fact that you get run over the 15th time you do this experiment doesn't preclude that the first 14 times you can get away with it.

It is called "undefined behaviour", and may include un-noticeable side-effects.
--
Mats

>> If your thread uses any of CRT fucntions, then it should use _beginthreadex to avoid certain types of memory leaks.
AfxBeginThead leaking or not...

>> ... and may include un-noticeable side-effects
In this case, it's a potential memory leak. Floating point exceptions and signal() may not work as expected as well: http://www.microsoft.com/msj/1099/win32/win321099.aspx

gg

Originally Posted by Codeplug

>> If your thread uses any of CRT fucntions, then it should use _beginthreadex to avoid certain types of memory leaks.
AfxBeginThead leaking or not...

>> ... and may include un-noticeable side-effects
In this case, it's a potential memory leak. Floating point exceptions and signal() may not work as expected as well: http://www.microsoft.com/msj/1099/win32/win321099.aspx

gg

Thank you very much for help
It doesn't seem to be available _beginthreadex under Microsoft Embedded Visual C++ 4.0 While it is available AfxBeginThread
So I guess I should always use AfxBeginThread?

In case you're using MFC, it wouldn't be a bad idea.

>> It doesn't seem to be available _beginthreadex under Microsoft Embedded Visual C++ 4.0
It was removed in CE 2.11. Under CE, just use CreateThread if not using MFC.

gg

Originally Posted by Codeplug

>> It doesn't seem to be available _beginthreadex under Microsoft Embedded Visual C++ 4.0
It was removed in CE 2.11. Under CE, just use CreateThread if not using MFC.

gg

thank you for support
I don't understand:
Why should I use CreateThread() if you said it's dangerous?
Has AfxBeginThread drawbacks?

It's not dangerous if you don't use MFC.
If you use MFC, use AfxBeginThread.
AfxBeginThread does not have any drawbacks. However, if can only be used if you use MFC.