bug#726: 23.0.60; OSX: Complete OS crash

bug#726: 23.0.60; OSX: Complete OS crash

[Markus Triska]

Let open7.el consist of the form:

   (let ((n 0))
     (while t
       (setq n (1+ n))
       (message "iteration: %s" n)
       (delete-process (start-process "bc" nil "bc"))))

When I do:

   $ emacs -Q --script open7.el

The whole OS crashes within about 500 iterations, and a gray box is
displayed stating that I must restart the computer. A shell script
that continuously starts and kills bc runs for long without problem:

   while true
   do
       bc &
       killall -9 bc
   done


In GNU Emacs 23.0.60.1 (i386-apple-darwin8.11.1, GTK+ Version 2.12.9)
 of 2008-08-15 on mt-computer.local
Windowing system distributor `The XFree86 Project, Inc', version 11.0.40400000
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: en.UTF-8
  value of $XMODIFIERS: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

bug#726: 23.0.60; OSX: Complete OS crash

[Stefan Monnier]

> The whole OS crashes within about 500 iterations, and a gray box is
> displayed stating that I must restart the computer. A shell script
> that continuously starts and kills bc runs for long without problem:

Does it die because of run-away processes or memory exhaustion?
If not, it's an OS bug.


        Stefan

bug#726: 23.0.60; OSX: Complete OS crash

[Markus Triska]

Stefan Monnier <monnier@iro.umontreal.ca> writes:

> Does it die because of run-away processes or memory exhaustion?

Most certainly not, since I have seen crashes within only 150
iterations. Note that only one subprocess is run at any time. When I do
not delete the subprocesses, there can be more than 1000 of them. I will
try to trace it down further. So far, when I slow down the program to
observe it more closely, the problem disappears. Also, I found that
today's Emacs 22.2.90 works for a long time without producing a crash on
the same program and system, while I can produce a crash with 23.0.60
every time in a few seconds.