 mutex before
signalling the condition, this guarantees that the condition cannot
be signalled (and thus ignored) between the time a thread locks the
mutex and the time it waits on the condition variable. 
</P>
<P><B>pthread_cond_timedwait</B> atomically unlocks <I>mutex</I> and
waits on <I>cond</I>, as <B>pthread_cond_wait</B> does, but it also
bounds the duration of the wait. If <I>cond</I> has not been
signalled within the amount of time specified by <I>abstime</I>, the
mutex <I>mutex</I> is re-acquired 