rb_thread_fd_select  456 include/ruby/intern.h int rb_thread_fd_select(int, rb_fdset_t *, rb_fdset_t *, rb_fdset_t *, struct timeval *);
rb_thread_fd_select 8452 io.c               n = rb_thread_fd_select(max, rp, wp, ep, tp);
rb_thread_fd_select 10130 io.c                   return rb_thread_fd_select(n, rfds, wfds, efds, timeout);
rb_thread_fd_select 3910 thread.c           r = rb_thread_fd_select(args->as.fd + 1,