Problem with processes that just won't die...

Question

Hi,
first off, hullo everybody
I'm new to Arch Linux, but I do already like it very much. I have just installed it on my workstation and it works fine, except for the following problem.
My home directory here is mounted via NFS from a central server. My username is malte (we're using YP/NIS for central authentication) and my home dir is /WW/home/malte/
The network file system that is mounted at boot time is /WW
malte@bombadil $ grep nfs /etc/fstab
quarterback:/WW    /WW           nfs       defaults               0      0
Everything is setup at boot time automatically and all works fine so far. However, when I reboot my machine using sudo reboot, or even when cleanly logging out and using the Shutdown/Reboot button in GDM, what happens is that Arch tries to unmount the net file systems (that is, /WW in this case), but fails and outputs
/WW: device is busy
(or something to that effect); so it gives up, and goes on shutting down all the other services, like the network etc. At the very end, when "Unmounting all filesystems", it then again tries to unmount the net file system, which of course won't work since the network is already shut down. It tries for about a minute or so before timing out, giving up and just rebooting
This of course is quite annoying, as I have to wait more than a minute each time I want to reboot (or I would have to press the reset button on the computer, which I really don't want to).
So why doesn't Arch succeed in unmounting the net file system when it should? Using lsof, I have traced down the problem further:
When I do not login as user in GDM after booting up the system, but immediately reboot again after GDM has just been started, there is no problem: /WW is unmounted properly, and my system reboots flawlessly.
The problem is when I log in to my WM as user. Even if I log out cleanly to GDM again, there are two processes belonging to user malte that go on living and that access to /WW/home/malte, and I suppose that is why unmounting fails at reboot time, saying the device is busy.
I have found out that (and which these processes are) by closely observing the output of watch 'lsof | grep WW' run as root on vc/1, just after I log out from my WM as user:
root@bombadil $ lsof | grep WW # executed closely after logging out as user malte
menu-cach 3410  malte  cwd       DIR               0,16     1536    8785908 /WW/home/malte (quarterback:/WW)
gam_serve 5391  malte  cwd       DIR               0,16     1536    8785908 /WW/home/malte (quarterback:/WW)
More information on those two processes:
root@bombadil $ ps aux | grep -e gam_serv -e menu-cach
malte     3410  0.0  0.1  41540  2680 ?        S    14:46   0:00 /usr/bin/menu-cached
malte     5391  0.0  0.0  17444  1476 ?        S    15:38   0:00 /usr/lib/gamin/gam_server
root      5473  0.0  0.0   9324   740 tty1     R+   15:38   0:00 grep -e gam-serv -e menu-cach
So! In short, even after logging out, menu-cached and gam_server keep on living, and access to /WW/home/malte, and that is why when I try to reboot, Arch does not succeed in unmounting /WW, and that is why it tries to unmount it again at a later time, after networking has already been shut down, and that is why it waits for a time-out for about a minute at the end of the reboot procedure.
In fact, gam_server only keeps on living for about 20 seconds after I logged out, then it is terminated. As for menu-cached, it goes on and on living, at least for 5 minutes, which is when I got tired of watching the output of watch 'lsof | grep WW' ;-)
Any ideas how this could be remedied? Ideally, I'd like to be able to reboot using sudo reboot rather than by logging out and using GDM to reboot, but I guess that then there will be even more processes alive and accessing the NFS file system when already Arch tries to unmount it.
Oh yes, maybe this is of some interest also:
malte@bombadil $ grep DAEMONS /etc/rc.conf
# DAEMONS
DAEMONS=(syslog-ng network portmap nfslock @netfs ypbind sshd crond)
Please help
Cheers,
Malte
Last edited by einheitlix (2009-03-31 14:20:35)

Answer 1

I have the same problem.  menu-caches doesn't die after user logs out of the session (don't have the gamin issue though).  I too am running LXDE.  When a different user logs in via gdm you'll still see the menu-cached processes for other users and I end up having to kill them as root.  I do believe this is a bug with either menu-caches and/or LXDE (or perhaps, more specifically, its session manager).  I've looked high and low through the system to figure out where menu-cached is invoked from and for any sort of associated configuration file to no avail.  I'm left with the conclusion that the invocation of menu-cached is hard-coded into start-lxde. 
As a ugly-hack workaround you might try making a shell script like the following in /etc/gdm/PostSession/ directory:
#!/bin/sh
killall menu-cached
This of course is only applicable for those running gdm as their display manager.  Also don't forget to make it executable.
I would imagine that menu-cached not closing on user logout is very much a bug.  Or perhaps, more precisely, something that hadn't gotten put in yet.  Afterall, LXDE is still a relatively new desktop.  A good one at that so far, if you don't mind some of the missing polish that its dev haven't had a chance to add yet.
If someone else knows a more elegant solution than that please let me, and the other LXDE users, know.
Last edited by PingFloyd (2009-04-04 02:08:29)