On Wed, Jul 23, 2014 at 10:41:06AM -0600, Chris Friesen wrote: > > Hi all, > > I was wondering if someone could point me to a doc describing the threading > model for nova. > > I know that we use greenthreads to map multiple threads of execution onto a > single native OS thread. And the python GIL results in limitations as well. > > According to the description at > "https://bugs.launchpad.net/tripleo/+bug/1203906"; for nova-api we > potentially fork off multiple instances because it's database-heavy and we > don't want to serialize on the database. > > If that's the case, why do we only run one instance of nova-conductor on a > single OS thread? > > And looking at nova-compute on a compute node with no instances running I > see 22 OS threads. Where do these come from? Are these related to libvirt? > Or are they forked the way that nova-api is?
Since native C API calls block greenthreads, nova has a native thread pool that is used for each libvirt API call. A similar thing is done for the libguestfs API calls and optionally you can do it in the database driver too. Basically any python module involving native C calls should be a candidate for a native thread pool Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :| _______________________________________________ OpenStack-dev mailing list OpenStack-dev@lists.openstack.org http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
