Custom Query (1030 matches)

Read-char-no-hang is supposed to return NIL if there is no more input available from the stream. But it hangs in the following particular example, when it's trying to read from the output stream of an external program, and that stream is still open but there's nothing on it:

? (defparameter *cat-process*
    (run-program "cat" nil
               :input :stream
               :output :stream
               :wait nil))
*CAT-PROCESS*
? (write-line "hi" (external-process-input-stream *cat-process*))
"hi"
? (finish-output (external-process-input-stream *cat-process*))
NIL
? (read-char-no-hang (external-process-output-stream *cat-process*))
#\h
? (read-char-no-hang (external-process-output-stream *cat-process*))
#\i
? (read-char-no-hang (external-process-output-stream *cat-process*))
#\Newline
? (read-char-no-hang (external-process-output-stream *cat-process*))
;; (hangs)

Another strange thing about the same situation is that LISTEN on that stream returns T even when there's no more to be read.

On moving a Lisp application to a newer Linux box, we get random, whacky behaviour. This is demonstrated by the following file:

=== process-test.lisp ===
(in-package :cl-user)

(defun big-sum (n)
  (let ((total n))
    (dotimes (i n total)
      (incf total i))))

(defun test ()
  (ccl:process-run-function "25" #'big-sum 250000000)
  (ccl:process-run-function "26" #'big-sum 260000000)
  (ccl:process-run-function "27" #'big-sum 270000000)
  (ccl:process-run-function "28" #'big-sum 280000000))

and session transcript:

$ uname -a
Linux startle 2.6.32-30-generic #59-Ubuntu SMP Tue Mar 1 21:30:21 UTC 2011 i686 GNU/Linux
$ ccl
Welcome to Clozure Common Lisp Version 1.6  (LinuxX8632)!
? (load "process-test.lisp")
#P"/home/startle/startle/process-test.lisp"
? (test)
#<PROCESS 28(5) [Reset] #x1828FA76>
? 
> Error: Fault during read of memory address #x634
> While executing: CCL::*-2, in process 26(3).


;;;
;;; #<PROCESS 26(3) [Active] #x182901B6> requires access to Shared Terminal Input
;;; Type (:y 3) to yield control to this thread.
;;;
> Error: value #<BOGUS object @ #x284E4729> is not of the expected type NUMBER.
> While executing: CCL::+-2, in process 27(4).


;;;
;;; #<PROCESS 27(4) [Active] #x1828FE16> requires access to Shared Terminal Input
;;; Type (:y 4) to yield control to this thread.
;;;
> Error: value #<Unprintable CCL::IMMEDIATE : #x34D0C3> is not of the expected type NUMBER.
> While executing: CCL::*-2, in process 28(5).


;;;
;;; #<PROCESS 28(5) [Active] #x1828FA76> requires access to Shared Terminal Input
;;; Type (:y 5) to yield control to this thread.
;;;

The exact error messages are variable. Above transcript from x86 Ubuntu 10.04 box; similar behaviour from x86 Centos 5.6. However, x86 Centos 5.3 (and earlier) does not show this, nor does Darwin/PPC (CCL 1.4).

I'm under Clozure Common Lisp Version 1.1-r9799S (DarwinX8632).

Compile IRONCLAD, the pure lisp encrpyt package, failed. See attach for backtrace.