Code review comment for lp:~vishvananda/nova/no-db-messaging

I'm having a little trouble grasping the multicall approach as shown here so I might be a bit confused.

It looks like the way this works is, when we schedule a volume to be created, we create an eventlet-based volume listener which will update the database as it hears back from the volume manager.

Maybe I'm mistaken about eventlet, but this implies that if for some reason the process terminates before the multicall has finished its last return, then the database won't be updated. Then, when the process is restarted, there will be no calling context remaining to handle the updates.

Would it be a more robust approach to create a permanently running VolumeListener that handles all volume update events?

Thanks!