Joining Threads

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The solution is to force main to wait until the other two threads are done.
That function is pthread_join, which takes two arguments;
- the thread ID of the thread to wait for.
- a pointer to a void* variable that will receive the finished thread s return value.
If you don't care about the thread return value, pass NULL as the second argument.
In the following code (see Fig. 5.3), main does not exit until threads are no longer using the argument structures.

Figure 5.3: Revised Main Function for thread-create2.c
$\begin{figure}\begin{center} \small \begin{verbatim}int main () { pthread_t t... ...fely return. */ return 0; }\end{verbatim} \normalsize \end{center} \end{figure}$
Make sure that any data you pass to a thread by reference is not deallocated;
- for local variables, which are deallocated when they go out of scope.
- for heap-allocated variables, which you deallocate by calling free.

**Figure 5.3:** Revised Main Function for thread-create2.c
$\begin{figure}\begin{center} \small \begin{verbatim}int main () { pthread_t t... ...fely return. */ return 0; }\end{verbatim} \normalsize \end{center} \end{figure}$

Cem Ozdogan 2007-05-16