[CRIU] Restarting Process in an LXC Container

[Pavel Emelyanov]

On 01/20/2015 02:43 PM, Andrew Vagin wrote:
> On Mon, Jan 19, 2015 at 06:09:47PM +0100, Thouraya TH wrote:
>> Hello :) thanks a lot for help.
>>
>> How do you enter into CT? Do you use screen or ssh?
>>
>> Before the Dumping Process:
>>
>> root at g-2:~# lxc-ls -f
>> NAME     STATE    IPV4  IPV6  GROUPS  AUTOSTART 
>> -----------------------------------------------
>> worker   STOPPED  -     -     -       NO          
>> root at g-2:~# lxc-start -n worker
>> root at g-2:~# lxc-attach -n worker
> 
> I've understood the problem and its causes. If you execute a process in
> CT, it lives in CT's pid namespaces, but it belongs to another process
> tree, becuase its parent is outside of the CT.
> 
> Currently CRIU is able to dump only one process tree. I am not sure that
> we will fix this problem in a near future. I can suggest you to use
> screen or tmux, they have to workaround your problem.

Even if we decide to, how would the semantics of this stuff look like?
I mean, you launched lxc-attach and see the output of the entered task.
Then someone checkpoints your container, carries one away then restores.
Where should the formerly entered tasks be re-attached to on restore?

I think the best we can do here is to abort dumping if we see such
dangling tasks.

Thanks,
Pavel