[openstack-dev] [oslo][devstack][all] ZooKeeper vs etcd for Tooz/DLM

Julien Danjou julien at danjou.info
Tue Mar 14 18:50:41 UTC 2017

On Tue, Mar 14 2017, Jay Pipes wrote:

> Not tooz, because I'm not interested in a DLM nor leader election library
> (that's what the underlying etcd3 cluster handles for me), only a fast service
> liveness/healthcheck system, but it shows usage of etcd3 and Google Protocol
> Buffers implementing a simple API for liveness checking and host maintenance
> reporting.

Cool cool. So that's the same feature that we implemented in tooz 3
years ago. It's called "group membership". You create a group, make
nodes join it, and you know who's dead/alive and get notified when their
status change.

> My plan is to push some proof-of-concept patches that replace Nova's
> servicegroup API with os-lively and eliminate Nova's use of an RDBMS for
> service liveness checking, which should dramatically reduce the amount of both
> DB traffic as well as conductor/MQ service update traffic.

Interesting. Joshua and Vilob tried to push usage of tooz group
membership a couple of years ago, but it got nowhere. Well, no, they got
2 specs written IIRC:


But then it died for whatever reasons on Nova side.

Julien Danjou
/* Free Software hacker
   https://julien.danjou.info */
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