;; the previous workarounds won't block while waiting for the first byte, but will block other srfi-18 threads after that. let's make a new port which never blocks instead!


;; don't block while reading anything from port p. port p must have an
;; associated filedescriptor.
(define (make-nonblocking-input-port p)
  (make-input-port (lambda ()
                     (thread-wait-for-i/o! (port->fileno p))
                     (read-char p))
                   (lambda () (char-ready? p))
                   (lambda () (close-input-port p))))


(begin
  (print "begin " (current-milliseconds))
  (thread-start!
   (lambda ()
     (pp 
      (call-with-input-pipe
       "sleep 1;  echo a ; sleep 1 ; echo b"
       (o (lambda (p) (read-string #f p)) make-nonblocking-input-port)))))
  (thread-yield!)

  (print "end " (current-milliseconds)))