pthread_mutex_lock(&score_mutex);
score = (score * (double)score_count + atof(line + 2)) /
(double)(score_count + 1);
++score_count;
pthread_mutex_unlock(&score_mutex);
pthread_mutex_lock(&score_mutex);
score = (score * (double)score_count + atof(line + 2)) /
(double)(score_count + 1);
++score_count;
pthread_mutex_unlock(&score_mutex);