if I got it right, they want you to restart hostd and vpxa
/etc/init.d/hostd restart
/etc/init.d/vpxa restart
this will cause the host management "freeze" for a couple of minutes indeed.
the VMs will keep running, but if Horizon will issue any management command in that timeframe it might fail, like for example reverting a VM in the IC desktop pool.
you'll have to resolve the errors if they will not be automagically solved.