[lxc-users] lxc_monitor exiting, but not cleaning monitor-fifo?

[Dwight Engen]

On Sat, 29 Mar 2014 23:39:33 +0100
Florian Klink <flokli at flokli.de> wrote:

> Hi,
> 
> when running multiple lxc actions in row using the command line
> tools, I sometimes observe the following state:
> 
> 
> - lxc-monitord is not running anymore
> - /run/lxc/var/lib/lxc/monitor-fifo still exists, but is "refusing
> connection"
> 
> In the logs, I then see the following:
> 
> 
> lxc-start 1395671045.703 ERROR    lxc_monitor - connect : backing off
> 10 lxc-start 1395671045.713 ERROR    lxc_monitor - connect : backing
> off 50 lxc-start 1395671045.763 ERROR    lxc_monitor - connect :
> backing off 100 lxc-start 1395671045.864 ERROR    lxc_monitor -
> connect : Connection refused
> 
> 
> ... and the command fails.
 
The only time I've seen this happen is if lxc-monitord is hard killed
so it doesn't have a chance to clean up and remove the socket.

> 
> A possible workaround would be checking for non-running lxc-monitord
> process but existing monitor-fifo file then removing the fifo if it
> exists before running the next lxc command, but thats ugly ;-)

Is there a good non-racy way to do this? I guess monitord could write
its pid in $LXCPATH and we could kill(pid, 0) it. 
 
> Is this behaviour known? Is there some missing "cleanup code" in
> lxc(_monitord) or why is it failing like this?
 
Currently it catches SIGILL, SIGSEGV, SIGBUS, and SIGTERM and cleans
up. Other than hard kill I'm not sure what else might cause it to exit
without cleaning up.

> Florian
> 
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