CreateThread和_beginthread的区别

转自： 冷秋魂的专栏
http://blog.csdn.net/primer_programer/archive/2007/12/26/1968158.aspx

CreateThread 是一个Win 32API 函数,_beginthread 是一个CRT(C Run-Time)函数，他们都是实现多线城的创建的函数，而且他们拥有相同的使用方法,相同的参数列表。

但是他们有什么区别呢？

一 般来说，从使用角度是没有多大的区别的，CRT函数中除了signal()函数不能在CreateThread创建的线城中使用外，其他的CRT 函数都可一正常使用，但是如果在CreateThread创建的线城中使用CRT函数的话，会产生一些Memory Leak.

下面是摘自KB的原话：

SUMMARY

All C Run-time functions except the signal() function work correctly when used in threads created by the CreateThread() function. However, depending on what CRT functions are called, there may be a small memory leak when threads are terminated. Calling strlen(), for example, does not trigger the allocation of the CRT thread data-block, and calling malloc(), fopen(), _open(), strtok(), ctime(), or localtime() causes allocation of a CRT per-thread data-block, which may cause a memory leak.

MORE INFORMATION

The "Programming Techniques" manual supplied with Visual C++ 32-bit Edition states that using CreateThread() in a program that uses Libcmt.lib causes many CRT functions to fail. Actually, the only function that should not be used in a thread created with CreateThread() is the signal() function.

There are two ways to create threads. One method involves using the CRT _beginthread() or _beginthreadex() (with Visual C++ 2.0 and later); the other method involves using the CreateThread() API. All CRT functions other than the signal() function work correctly in threads created with either _beginthread() or CreateThread(). However, there are some problems involved with using CRT functions in threads created with CreateThread().

Threads that are created and terminated with the CreateThread() and ExitThread() Win32 API functions do not have memory that is allocated by the CRT for static data and static buffers cleaned up when the thread terminates. Some examples of this type of memory are static data for errno and _doserrno and the static buffers used by functions such as asctime(), ctime(), localtime(), gmtime(), and mktime(). Using CreateThread() in a program that uses the CRT (for example, links with LIBCMT.LIB) may cause a memory leak of about 70-80 bytes each time a thread is terminated.

To guarantee that all static data and static buffers allocated by the CRT are cleaned up when the thread terminates, _beginthreadex() and _endthreadex() should be used when creating a thread. The _beginthreadex() function includes the same parameters and functionality as CreateThread().