void pthread_exit(void *value_ptr) {
Thread * th = thread_current();
model->switch_to_master(new ModelAction(THREAD_FINISH, std::memory_order_seq_cst, th));
void pthread_exit(void *value_ptr) {
Thread * th = thread_current();
model->switch_to_master(new ModelAction(THREAD_FINISH, std::memory_order_seq_cst, th));