From: michael.cadilhac@lrde.org (Michaël Cadilhac)
Cc: Agustin Martin <agustin.martin@hispalinux.es>,
emacs-devel@gnu.org, "Kim F. Storm" <storm@cua.dk>
Subject: Re: delete-process bug
Date: Mon, 29 May 2006 13:39:54 +0200 [thread overview]
Message-ID: <87pshx2h6d.fsf@lrde.org> (raw)
In-Reply-To: <jwvmzd1ol49.fsf-monnier+emacs@gnu.org> (Stefan Monnier's message of "Sun, 28 May 2006 19:54:07 -0400")
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Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> In fact, there is already a configuration that would lead to the non
>> deletion of the PID from the list:
>
>> - Call to delete_process,
>> - Interrupted by a signal before inserting in deleted_processes_list ,
>> - Deletion from process_alist,
>
> How can this happen? Are you saying that a signal handler may delete the
> process from process_alist? Which signal handler can do that?
You're right, it's not its job.
> I do think there's a leak but it goes like this:
>
> - catch the SIGCHLD signal
> - start processing delete-process, which will add the PID to
> deleted_pid_list even though the signal has already been caught so the pid
> won't get a chance to be removed.
> I guess we could check the process's status after adding it to
> deleted_pid_list, to catch this case.
I think it would be OK. Here's the new (new new) version of the patch.
The kill_process part is not called if the process is already
terminated.
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[-- Type: text/x-patch, Size: 4516 bytes --]
Index: src/process.c
===================================================================
RCS file: /sources/emacs/emacs/src/process.c,v
retrieving revision 1.481
diff -c -r1.481 process.c
*** src/process.c 8 May 2006 05:19:42 -0000 1.481
--- src/process.c 29 May 2006 11:36:31 -0000
***************
*** 778,783 ****
--- 778,793 ----
return proc;
}
+
+ #ifdef SIGCHLD
+ /* Fdelete_process promises to immediately forget about the process, but in
+ reality, Emacs needs to remember those processes until they have been
+ treated by sigchld_handler; otherwise this handler would consider the
+ process as being synchronous and say that the synchronous process is
+ dead. */
+ static Lisp_Object deleted_pid_list;
+ #endif
+
DEFUN ("delete-process", Fdelete_process, Sdelete_process, 1, 1, 0,
doc: /* Delete PROCESS: kill it and forget about it immediately.
PROCESS may be a process, a buffer, the name of a process or buffer, or
***************
*** 799,810 ****
}
else if (XINT (p->infd) >= 0)
{
! Fkill_process (process, Qnil);
! /* Do this now, since remove_process will make sigchld_handler do nothing. */
! p->status
! = Fcons (Qsignal, Fcons (make_number (SIGKILL), Qnil));
! XSETINT (p->tick, ++process_tick);
! status_notify (p);
}
remove_process (process);
return Qnil;
--- 809,839 ----
}
else if (XINT (p->infd) >= 0)
{
! #ifdef SIGCHLD
! Lisp_Object symbol;
!
! /* No problem storing the pid here, as it is still in Vprocess_alist. */
! deleted_pid_list = Fcons (make_fixnum_or_float (p->pid),
! /* GC treated elements set to nil. */
! Fdelq (Qnil, deleted_pid_list));
! /* If the process has already signaled, remove it from the list. */
! if (p->raw_status_new)
! update_status (p);
! symbol = p->status;
! if (CONSP (p->status))
! symbol = XCAR (p->status);
! if (EQ (symbol, Qsignal) || EQ (symbol, Qexit))
! Fdelete (make_fixnum_or_float (p->pid), deleted_pid_list);
! else
! #endif
! {
! Fkill_process (process, Qnil);
! /* Do this now, since remove_process will make sigchld_handler do nothing. */
! p->status
! = Fcons (Qsignal, Fcons (make_number (SIGKILL), Qnil));
! XSETINT (p->tick, ++process_tick);
! status_notify (p);
! }
}
remove_process (process);
return Qnil;
***************
*** 6373,6378 ****
--- 6402,6418 ----
/* Find the process that signaled us, and record its status. */
+ #ifdef SIGCHLD
+ /* The process can have been deleted by Fdelete_process. */
+ tail = Fmember (make_fixnum_or_float (pid), deleted_pid_list);
+ if (!NILP (tail))
+ {
+ Fsetcar (tail, Qnil);
+ goto sigchld_end_of_loop;
+ }
+ #endif
+
+ /* Otherwise, if it is asynchronous, it is in Vprocess_alist. */
p = 0;
for (tail = Vprocess_alist; GC_CONSP (tail); tail = XCDR (tail))
{
***************
*** 6424,6431 ****
EMACS_SET_SECS_USECS (*input_available_clear_time, 0, 0);
}
! /* There was no asynchronous process found for that id. Check
! if we have a synchronous process. */
else
{
synch_process_alive = 0;
--- 6464,6471 ----
EMACS_SET_SECS_USECS (*input_available_clear_time, 0, 0);
}
! /* There was no asynchronous process found for that pid: we have
! a synchronous process. */
else
{
synch_process_alive = 0;
***************
*** 6442,6447 ****
--- 6482,6491 ----
EMACS_SET_SECS_USECS (*input_available_clear_time, 0, 0);
}
+
+ sigchld_end_of_loop:
+ ;
+
/* On some systems, we must return right away.
If any more processes want to signal us, we will
get another signal.
***************
*** 6843,6848 ****
--- 6887,6895 ----
FD_SET (0, &input_wait_mask);
Vprocess_alist = Qnil;
+ #ifdef SIGCHLD
+ deleted_pid_list = Qnil;
+ #endif
for (i = 0; i < MAXDESC; i++)
{
chan_process[i] = Qnil;
***************
*** 6981,6986 ****
--- 7028,7036 ----
staticpro (&Qlast_nonmenu_event);
staticpro (&Vprocess_alist);
+ #ifdef SIGCHLD
+ staticpro (&deleted_pid_list);
+ #endif
DEFVAR_BOOL ("delete-exited-processes", &delete_exited_processes,
doc: /* *Non-nil means delete processes immediately when they exit.
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--
| Michaël `Micha' Cadilhac | Un certain Blaise Pascal |
| Epita/LRDE Promo 2007 | etc... etc... |
| http://www.lrde.org/~cadilh_m | -- Prévert (Les paris stupides) |
`-- - JID: micha@amessage.be --' - --'
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next prev parent reply other threads:[~2006-05-29 11:39 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-24 19:36 Ispell loads dict twice Michaël Cadilhac
2006-04-26 10:14 ` Agustin Martin
2006-04-26 21:58 ` Michaël Cadilhac
2006-05-23 18:26 ` Michaël Cadilhac
2006-05-24 11:28 ` Agustin Martin
2006-05-25 10:57 ` delete-process bug (was: Ispell loads dict twice.) Michaël Cadilhac
2006-05-25 12:19 ` Agustin Martin
2006-05-25 14:55 ` delete-process bug Stefan Monnier
2006-05-25 14:59 ` David Kastrup
2006-05-25 15:17 ` Michaël Cadilhac
2006-05-25 15:26 ` David Kastrup
2006-05-25 19:40 ` Stefan Monnier
2006-05-25 23:51 ` Kim F. Storm
2006-05-26 4:49 ` Richard Stallman
2006-05-26 13:03 ` Stefan Monnier
2006-05-26 2:22 ` Richard Stallman
2006-05-26 11:29 ` Michaël Cadilhac
2006-05-27 3:36 ` Richard Stallman
2006-05-26 13:10 ` Stefan Monnier
2006-05-26 17:27 ` Michael Mauger
2006-05-27 9:19 ` Michaël Cadilhac
2006-05-27 14:16 ` Stefan Monnier
2006-05-27 14:29 ` Michaël Cadilhac
2006-05-28 16:01 ` Michaël Cadilhac
2006-05-28 18:00 ` Stefan Monnier
2006-05-28 18:32 ` Michaël Cadilhac
2006-05-28 19:48 ` Stefan Monnier
2006-05-28 20:26 ` Michaël Cadilhac
2006-05-28 21:15 ` Kim F. Storm
2006-05-28 21:36 ` Michaël Cadilhac
2006-05-28 23:54 ` Stefan Monnier
2006-05-29 11:39 ` Michaël Cadilhac [this message]
2006-05-29 8:22 ` Kim F. Storm
2006-05-29 8:50 ` David Kastrup
2006-05-29 19:04 ` Eli Zaretskii
2006-05-29 19:27 ` Eli Zaretskii
2006-05-29 21:42 ` Kim F. Storm
2006-05-29 22:08 ` Eli Zaretskii
2006-05-29 3:32 ` Eli Zaretskii
2006-05-29 8:14 ` Kim F. Storm
2006-05-29 10:59 ` Michaël Cadilhac
2006-05-29 19:25 ` Eli Zaretskii
2006-05-29 20:04 ` Michaël Cadilhac
2006-05-29 21:24 ` Eli Zaretskii
2006-05-29 21:42 ` Michaël Cadilhac
2006-05-29 22:11 ` Eli Zaretskii
2006-05-29 22:32 ` Michaël Cadilhac
2006-05-30 12:11 ` Kim F. Storm
2006-05-30 12:42 ` Michaël Cadilhac
2006-05-30 14:26 ` Kim F. Storm
2006-05-30 15:13 ` Michaël Cadilhac
2006-06-01 14:06 ` Kim F. Storm
2006-06-01 14:20 ` Michaël Cadilhac
2006-06-01 14:29 ` Kim F. Storm
2006-06-01 16:05 ` Michaël Cadilhac
2006-06-02 7:46 ` Kim F. Storm
2006-06-01 16:41 ` Agustin Martin
2006-06-01 16:55 ` Michaël Cadilhac
2006-05-29 23:07 ` Agustin Martin
2006-05-25 23:52 ` delete-process bug (was: Ispell loads dict twice.) Kim F. Storm
2006-06-06 20:45 ` Ispell loads dict twice Michaël Cadilhac
2006-06-09 13:02 ` Kim F. Storm
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