[openstack-dev] Do we need lock fencing?

Joshua Harlow harlowja at fastmail.com
Sat Feb 20 00:05:05 UTC 2016

Hi all,

After reading over the following interesting article about redis and 
redlock (IMHO it's good overview of distributed locking in general):

(I personally recommend people read the whole article as well, as it's 
rather interesting, as well as the response from the redis author at 

It got me wondering if with all the locking and such that is getting 
used in openstack (distributed or not) that as we move to more 
distributed locking mechanisms (for scale reasons, HA, active-active...) 
that we might need to have a way to fence modifications of a storage 
entry (say belonging to a resource, ie a volume, a network...) with a 
token (or sequence-id) so that the problems mentioned in that blog do 
not affect openstack (apparently issues like it have affected hbase) and 
the more we think about it now (vs. later) the better we will be.

Anyone have any thoughts on this?

Perhaps tooz can along with its lock API also provide a token for each 
lock that can be used to interact with a storage layer (and that token 
can checked by the storage layer to avoid storage layer corruption).


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