tid_reader = calloc(nr_readers, sizeof(*tid_reader));
tid_writer = calloc(nr_writers, sizeof(*tid_writer));
count_reader = calloc(nr_readers, sizeof(*count_reader));
tid_reader = calloc(nr_readers, sizeof(*tid_reader));
tid_writer = calloc(nr_writers, sizeof(*tid_writer));
count_reader = calloc(nr_readers, sizeof(*count_reader));