Re: Problem with GLib.spawn_async / GLib.child_watch_add

["Jasper St. Pierre" <jstpierre mecheye net>]

On Mon, May 14, 2012 at 2:02 PM, Neil Bird <gnome fnxweb com> wrote:
>
>  I need to be able to run a command from an extension, and as this may take
> a while I want to run it async and catch the process completing. However,
> there's something screwy with spawn_async that's stopping the
> child_watch_add from working.  gnome-shell itself has code akin to this, so
> I don't know what I'm doing wrong.
>
>  In the following test case, a “sleep” is spawned, but if you do a “pstree
> -pal” while it's active, the child process is actually not created as a
> child.  So, when the child_watch_add tries to do a waitpid() call (ref.
> strace -eprocess -f) it fails with ECHILD (pid is not a child) and my
> callback never occurs.
>
>  Is it broken or am I doing something stupid?
>
>
> #!/usr/bin/gjs
>
> const GLib = imports.gi.GLib;
> const Gtk = imports.gi.Gtk;
>
> // Initialize GTK+
> Gtk.init(null, 0);
>
>
> // Supposed to handle end of process
> function jobby()
> {
>    print("In jobby");
> }
>
>
> let [success, pid] = GLib.spawn_async(
>    null,
>    ['sleep', '5'],
>    null,
>    GLib.SpawnFlags.SEARCH_PATH | GLib.SpawnFlags.NO_NOT_REAP_CHILD,

DO_NOT_REAP_CHILD

>    null );
> if (success  &&  pid != 0)
> {
>    // Wait for answer
>    print("created process, pid=" + pid);
>    GLib.child_watch_add( GLib.PRIORITY_DEFAULT, pid, function(pid,status) {
>        GLib.spawn_close_pid(pid);
>        print("process completed, status=" + status);
>        jobby();
>    });
> }
> else
> {
>    print("failed process creation");
> }
>
> // Main loop
> Gtk.main();
>
>
> --
> [phoenix@fnx ~]# rm -f .signature
> [phoenix@fnx ~]# ls -l .signature
> ls: .signature: No such file or directory
> [phoenix@fnx ~]# exit
>
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-- 
  Jasper