[Octave-bug-tracker] [bug #37591] system with async option results in zombie processes

[Mike Miller]

URL:
  <http://savannah.gnu.org/bugs/?37591>

                 Summary: system with async option results in zombie processes
                 Project: GNU Octave
            Submitted by: mtmiller
            Submitted on: Wed 17 Oct 2012 08:37:48 PM EDT
                Category: Libraries
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Other
                  Status: None
             Assigned to: None
         Originator Name: 
        Originator Email: 
             Open/Closed: Open
         Discussion Lock: Any
                 Release: dev
        Operating System: GNU/Linux

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Details:

Each call of


system (cmd, [], "async");


leaves a zombie process on Linux, probably MacOS and other unices as well. The
sigchld_handler function is called for each process that exits, but nothing is
done to clean up these processes until Octave exits. Exiting Octave simply
allows init to clean up the leftovers.

Example:


octave:1> system ("ps");
  PID TTY          TIME CMD
  528 pts/3    00:00:00 lt-octave
 3357 pts/3    00:00:00 sh
 3358 pts/3    00:00:00 ps
19089 pts/3    00:00:00 bash
octave:2> system ("uname", [], "async");
octave:3> system ("uname", [], "async");
octave:4> system ("uname", [], "async");
octave:5> system ("uname", [], "async");
octave:6> system ("ps");
  PID TTY          TIME CMD
  528 pts/3    00:00:00 lt-octave
 3375 pts/3    00:00:00 sh <defunct>
 3377 pts/3    00:00:00 sh <defunct>
 3380 pts/3    00:00:00 sh <defunct>
 3384 pts/3    00:00:00 sh <defunct>
 3393 pts/3    00:00:00 sh
 3394 pts/3    00:00:00 ps
19089 pts/3    00:00:00 bash


A more common way to trigger this behavior is the edit command, which defaults
to async mode when starting the editor.

If edit or system are called enough times, the user can overrun the process
limit and no more processes can be started until Octave exits.




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