Re: possible typo in multithreading website

James Kanze <>
Mon, 13 Apr 2009 04:14:47 -0700 (PDT)
On Apr 12, 1:28 pm, wrote:

I have read the above from a multithreading in c++ tutorial:



Listing 2. Still a race condition

void* workerThread(void*)
    while(sharedCounter > 0)

The solution is to use a mutex to synchronise the threads with
respect to the test and update. Another way of saying this is
that we need to define a critical section in which we both
test and update the sharedCounter. The next section introduces
mutexes and solves the example race condition.


I believe that the correct signature of workerThread is void
workerThread(void) rather than void* workerThread(void*)

It depends. If the function is the one passed to
pthread_create, then the correct signature in C++ is:

    extern "C" void* workerThread( void* ) ;

Nothing else should pass the compiler. (G++ is buggy here, and
accepts the code without the `extern "C"'.)

For Windows, it should be:

    DWORD WINAPI workerThread( __in LPVOID ) ;

(I'm not sure what all those macros mean: DWORD sounds like a
long long, WINAPI is probably some implementation extension
controling the linkage---the equivalent of `extern "C"' in
standard C++, and LPVOID a long pointer to void, except that I
didn't think that Windows supported long (48 bit) pointers.)

James Kanze (GABI Software)
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