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

[Florian Klink]

Am 31.03.2014 20:10, schrieb 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.

Here, it's happening quite frequently. However, the script never kills
lxc-monitord on its own, it just tries to detect and fix this state by
removing the socket file...

> 
>>
>> 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.

I shutdown containers with `lxc-stop -n container-name`
(lxc.stopsignal=30 (SIGPWR)), however this signal should never go to
lxc_monitord, right?

> 
>> Florian
>>
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>