rb_fd_zero        230 include/ruby/intern.h #define rb_fd_zero(f)		((f)->fdset->fd_count = 0)
rb_fd_zero        242 include/ruby/intern.h #define rb_fd_zero(f)	FD_ZERO(f)
rb_fd_zero       2167 thread.c       rb_fd_zero(rb_fdset_t *fds)