libvirt users - Mar 2016 - How to test if a console session is active?

I use libvirt to manage a container based environment. Is there an 
efficient method for testing if someone has a console session open for a 
given container? The approach I'm using at the moment is to use lsof and 
check if there is an entry for the container's console pts device. For 
example, I can determine a container's console device from its xml 
definition:

# virsh dumpxml vm-00|grep -A 4 pty
     <console type='pty' tty='/dev/pts/3'>
       <source path='/dev/pts/3'/>
       <target type='lxc' port='0'/>
       <alias name='console0'/>
     </console>

Once I have pts device, I can do something like

# if lsof /dev/pts/3; then echo "Container vm-00 has an active console 
session"; fi

This all works fine but we've found that lsof is very expensive. Is 
there a more efficient means to make this active console check?

Peter