Emacsclient, multiple displays and hanging

Emacsclient, multiple displays and hanging

[Greg Detre]

Dear all,

I try to keep the same Emacs session on my laptop running for days and
weeks at a time. When I'm at work, I want to be able to use that same
emacs session on my desktop. So I sit at my desktop and ssh into my
laptop, using emacsclient and 'make-frame-on-display' to bring up a
new emacsclient session on my desktop, continuing where I left off.
This works phenomenally for me.

The problem comes when I remove my laptop. If I forgot to close all
the running emacsclient windows on my desktop, then emacs on my laptop
hangs (since it's waiting for some kind of X input from the
emacsclient running on my desktop). Obviously the solution is to
always shut all the emacsclients on my desktop before unplugging my
laptop, but I forget about twice a week, and have to kill -9 my laptop
emacs :(

I've spent a fair while scouring emacsclient tips and documentation,
but nobody appears to have mentioned this issue. Does anybody have any
ideas for how to fix or work around this?

Yours,
   Greg

P.S. I wrote a tiny wrapper for Emacsclient to try and make it
friendlier for the use case I outlined above. Feel free to grab it
from here:

http://gregdetre.blogspot.com/2007/05/my-take-on-emacsclient.html

Re: Emacsclient, multiple displays and hanging

[Eli Zaretskii]

> From: Greg Detre <gdetre@gmail.com>
> Date: Sun, 30 Sep 2007 04:09:44 -0000
> 
> I forget about twice a week, and have to kill -9 my laptop emacs :(

As a quick workaround, does it work to "kill -15"?  If it does, then I
think you will see that Emacs at least saves the session in a way that
it can be later restored, and your edits are not lost.

Re: Emacsclient, multiple displays and hanging

[Colin S. Miller]

Greg Detre wrote:
> Dear all,
> 
> When I'm at work, I want to be able to use that same
> emacs session on my desktop. So I sit at my desktop and ssh into my
> laptop, using emacsclient and 'make-frame-on-display' to bring up a
> new emacsclient session on my desktop, continuing where I left off.
> 
> The problem comes when I remove my laptop. If I forgot to close all
> the running emacsclient windows on my desktop, then emacs on my laptop
> hangs (since it's waiting for some kind of X input from the
> emacsclient running on my desktop). Obviously the solution is to
> always shut all the emacsclients on my desktop before unplugging my
> laptop, but I forget about twice a week, and have to kill -9 my laptop
> emacs :(
> 

Greg,

the following function will kill all X-Frames on a named display

(defun csm-kill-frames-on-device (display)
   "kill all frames on display DISPLAY"

   (let ((dvce))
     (loop for frm in (frame-list)
       do
       (progn
         (setq dvce (frame-device frm))
         (if (device-on-window-system-p dvce)
               (if (string-equal (device-connection dvce) display)
                   (delete-frame frm)))))))

or

(defun csm-kill-all-non-local-x-frames ()
   "kill all frames that are not on :0.0"

   (let ((dvce))
     (loop for frm in (frame-list)
       do
       (progn
         (setq dvce (frame-device frm))
         (if (device-on-window-system-p dvce)
               (if (not (string-equal (device-connection dvce) '":0.0"))
           (delete-frame frm)))))))


If you close your laptop's lid before unplugging it, you can catch the
kill -SIGPWR with an external script, have it run emacsclient, calling either the
above functions to kill connections from your desktop.

SIGPWR is sent when a UPS connected machine switches to UPS power, I'd assume it's also sent
when a machine is hibernated/suspended (or resumed).


I can't see of a way to handle signals inside emacs, so an external script is a necessary evil.

HTH,
Colin S. Miller


-- 
Replace the obvious in my email address with the first three letters of the hostname to reply.

Re: Emacsclient, multiple displays and hanging

[Greg Detre]

Colin,

Thank you very much indeed. I'll try that.

g

On Oct 1, 4:30 pm, "Colin S. Miller" <no-spam-
thank-...@csmiller.demon.co.uk> wrote:
> Greg Detre wrote:
> > Dear all,
>
> > When I'm at work, I want to be able to use that same
> > emacs session on my desktop. So I sit at my desktop and ssh into my
> > laptop, using emacsclient and 'make-frame-on-display' to bring up a
> > new emacsclient session on my desktop, continuing where I left off.
>
> > The problem comes when I remove my laptop. If I forgot to close all
> > the running emacsclient windows on my desktop, then emacs on my laptop
> > hangs (since it's waiting for some kind of X input from the
> > emacsclient running on my desktop). Obviously the solution is to
> > always shut all the emacsclients on my desktop before unplugging my
> > laptop, but I forget about twice a week, and have to kill -9 my laptop
> > emacs :(
>
> Greg,
>
> the following function will kill all X-Frames on a named display
>
> (defun csm-kill-frames-on-device (display)
>    "kill all frames on display DISPLAY"
>
>    (let ((dvce))
>      (loop for frm in (frame-list)
>        do
>        (progn
>          (setq dvce (frame-device frm))
>          (if (device-on-window-system-p dvce)
>                (if (string-equal (device-connection dvce) display)
>                    (delete-frame frm)))))))
>
> or
>
> (defun csm-kill-all-non-local-x-frames ()
>    "kill all frames that are not on :0.0"
>
>    (let ((dvce))
>      (loop for frm in (frame-list)
>        do
>        (progn
>          (setq dvce (frame-device frm))
>          (if (device-on-window-system-p dvce)
>                (if (not (string-equal (device-connection dvce) '":0.0"))
>            (delete-frame frm)))))))
>
> If you close your laptop's lid before unplugging it, you can catch the
> kill -SIGPWR with an external script, have it run emacsclient, calling either the
> above functions to kill connections from your desktop.
>
> SIGPWR is sent when a UPS connected machine switches to UPS power, I'd assume it's also sent
> when a machine is hibernated/suspended (or resumed).
>
> I can't see of a way to handle signals inside emacs, so an external script is a necessary evil.
>
> HTH,
> Colin S. Miller
>
> --
> Replace the obvious in my email address with the first three letters of the hostname to reply.

Re: Emacsclient, multiple displays and hanging

[Greg Detre]

On Sep 30, 11:54 am, Eli Zaretskii <e...@gnu.org> wrote:
> > From: Greg Detre <gde...@gmail.com>
> > Date: Sun, 30 Sep 2007 04:09:44 -0000
>
> > I forget about twice a week, and have to kill -9 my laptop emacs :(
>
> As a quick workaround, does it work to "kill -15"?  If it does, then I
> think you will see that Emacs at least saves the session in a way that
> it can be later restored, and your edits are not lost.

Thanks, Eli. That's not a bad idea, but I've found that I need to use
kill -9 usually.

g

Re: Emacsclient, multiple displays and hanging

[Andrew Walrond]

>> Greg Detre wrote:
>>> Dear all,
>>> When I'm at work, I want to be able to use that same
>>> emacs session on my desktop. So I sit at my desktop and ssh into my
>>> laptop, using emacsclient and 'make-frame-on-display' to bring up a
>>> new emacsclient session on my desktop, continuing where I left off.
>>> The problem comes when I remove my laptop. If I forgot to close all
>>> the running emacsclient windows on my desktop, then emacs on my laptop
>>> hangs (since it's waiting for some kind of X input from the
>>> emacsclient running on my desktop). Obviously the solution is to
>>> always shut all the emacsclients on my desktop before unplugging my
>>> laptop, but I forget about twice a week, and have to kill -9 my laptop
>>> emacs :(

I haven't tried the emacsclient stuff yet, but I always run gnu screen,
then emacs within that. If you lose the connection, you'll just get
'detached' by gnu screen; no hung processes at all. And you can always
reattach with 'screen -r'

I wouldn't be without gnu screen now. And my .screenrc file is almost as
important to me as .emacs ;)

Andrew Walrond

Re: Emacsclient, multiple displays and hanging

[poppyer]

Andrew Walrond <andrew@walrond.org> writes:


> I haven't tried the emacsclient stuff yet, but I always run gnu screen,
> then emacs within that. If you lose the connection, you'll just get
> 'detached' by gnu screen; no hung processes at all. And you can always
> reattach with 'screen -r'
>
> I wouldn't be without gnu screen now. And my .screenrc file is almost as
> important to me as .emacs ;)
>
Same with me :)
any good tips about your .screenrc file?


-- 

Re: Emacsclient, multiple displays and hanging

[Andrew Walrond]

poppyer wrote:
> any good tips about your .screenrc file?
> 

Gnu Screen's equivalent of emacs inhibit-startup-message:

	startup_message off

Since I use emacs 24/7 and need C-a, change screens escape to C-z (and
C-z to C-z z)

	escape ^zz

I copied this hardstatus config from the example .screenrc I think

	hardstatus on
	hardstatus alwayslastline
	hardstatus string "%{.bW}%-w%{.rW}%n %t%{-}%+w %=%{..G} %H %{..Y} %m/%d
%C%a "

This allows emacs, less etc to reinstate the screen when they exit:

	altscreen

And a lot of stuff doesn't like TERM=screen, so I change it

	term xterm

Anyone else got useful .screenrc tips?

Andrew Walrond

Re: Emacsclient, multiple displays and hanging

[Stefan Monnier]

> the following function will kill all X-Frames on a named display
> (defun csm-kill-frames-on-device (display)
>   "kill all frames on display DISPLAY"

In the trunk version of Emacs-CVS, there's `close-display-connection'.

But admittedly, Emacs should handle this case more transparently.
Try M-x report-emacs-bug to post this feature request.


        Stefan