[openstack-dev] design question : green thread model

Johannes Erdfelt johannes at erdfelt.com
Wed Jan 28 17:08:13 UTC 2015

On Wed, Jan 28, 2015, murali reddy <muralimmreddy at gmail.com> wrote:
> I am trying to understand how a nova component can be run parallely on a
> host. From the developer reference documentation it seems to indicate that
> all the openstack services use green thread model of threading. Is it the
> only model of parallelism for all the components or multiple processes can
> be used for a nova service on a host. Does nova.service which seems to do
> os.fork is being used to fork multiple processes for a nova service?

Multiple processes are used in some places, for instance, nova-api can
fork multiple processes. Each process would also use greenthreads as

However, most services don't use multiple processes (at least in Nova).


More information about the OpenStack-dev mailing list