> COND is accessed before cond_signal() in child thread
yes
> and after cond_wait() in parent thread.
no:
while (COND != 1) {
fprintf(stderr, "Wait: COND: %d\n", COND);
pthread_cond_wait(&CV, &MU);
}
If the parent only accessed COND after cond_wait, then Helgrind would
not complain, as then it would understand that "exclusive ownership" is
transferred from child to parent by the signal/wait pair. However, both
parent and child access it before the signal/wait pair, COND is marked
as being in shared ownership, and the above doesn't apply.
> >> If you change the order of these two lines, to
>
> Sure. But thread_join is not what is usually done in presence of thread
> pools...
> Threads tend to live forever.
> This program is just a short reproducer.
Yes. I suspect what you are seeing is a problem to do with memory
recycling. See Helgrind manual Sec 7.5 point 2.
Can you send a slightly bigger reproducer, which has the child thread
doing a few units of work that are passed to it from the parent thread?
J
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