Excerpts from Monsyne Dragon's message of 2012-03-02 16:10:01 -0500: > > On Mar 2, 2012, at 9:17 AM, Jay Pipes wrote: > > > On 03/02/2012 05:34 AM, Day, Phil wrote: > >> In our experience (running clusters of several hundred nodes) the DB > >> performance is not generally the significant factor, so making its calls > >> non-blocking gives only a very small increase in processing capacity and > >> creates other side effects in terms of slowing all eventlets down as they > >> wait for their turn to run. > > > > Yes, I believe I said that this was the case at the last design summit -- > > or rather, I believe I said "is there any evidence that the database is a > > performance or scalability problem at all"? > > > >> That shouldn't really be surprising given that the Nova DB is pretty small > >> and MySQL is a pretty good DB - throw reasonable hardware at the DB server > >> and give it a bit of TLC from a DBA (remove deleted entries from the DB, > >> add indexes where the slow query log tells you to, etc) and it shouldn't > >> be the bottleneck in the system for performance or scalability. > > > > ++ > > > >> We use the python driver and have experimented with allowing the eventlet > >> code to make the db calls non-blocking (its not the default setting), and > >> it works, but didn't give us any significant advantage. > > > > Yep, identical results to the work that Mark Washenberger did on the same > > subject. > > > > Has anyone thought about switching to gevent? It's similar enough to > eventlet that the port shouldn't be too bad, and because it's event loop is > in C, (libevent), there are C mysql drivers (ultramysql) that will work with > it without blocking.
Switching to gevent won't fix the structural problems with the codebase, that nescitated sleeps for greenlet switching. A refactoring to an architecture more amenable to decomposing api requests into discrete tasks executed that are yieldable would help. incidentally, ultramysql is not dbapi compliant, and won't work with sqlalchemy. -kapil _______________________________________________ Mailing list: https://launchpad.net/~openstack Post to : openstack@lists.launchpad.net Unsubscribe : https://launchpad.net/~openstack More help : https://help.launchpad.net/ListHelp
