rb_thread_select 737 ext/socket/socket.c     rb_thread_select(fd+1, &fds, 0, 0, 0);
rb_thread_select 748 ext/socket/socket.c     rb_thread_select(fd+1, 0, &fds, 0, 0);
rb_thread_select 271 io.c               rb_thread_select(f + 1, &rfds, NULL, NULL, NULL);
rb_thread_select 281 io.c               rb_thread_select(f + 1, NULL, &wfds, NULL, NULL);
rb_thread_select 3137 io.c               n = rb_thread_select(max, rp, wp, ep, tp);