[openstack-dev] [Openstack][Nova] Slow Nova API Calls from periodic-tempest-devstack-vm-check-hourly

Chris Behrens cbehrens at codestud.com
Mon Jan 7 07:41:38 UTC 2013

Try enabling DB pool code

On Jan 6, 2013, at 10:46 PM, Mark McLoughlin <markmc at redhat.com> wrote:

> On Fri, 2013-01-04 at 11:58 -0800, Joe Gordon wrote:
>> Conclusion
>> =========
>> Nova REST calls take way long, even in small scale devstack/tempest
>> testing.  We should spend resources on fixing this for Grizzly.  I would
>> like to start a dialog on how we can fix this and see if anyone wants to
>> volunteer help.  Below are a few possible ideas of things that will help us
>> make the REST calls faster.
>> * Continuously track REST API times of devstack/tempest jobs, to identify
>> slow API calls and watch for trends.  (logstash + statsd?)
>> * Identify the underlying cause of the slow performance.  It looks like
>> nova.db.api may be partially responsible, but not the only issue?  What
>> else is a bottleneck?
>> * Enable millisecond level time logging
>> https://review.openstack.org/#/c/18933/
>> * Add an option in devstack to enable python profiling?  Whats best way to
>> do this?
>> * Make more REST API related code asynchronous (via RPC)
> Summary is we're randomly seeing a multi-second delay in nova-api
> between the time a HTTP request is received and we send an AMQP message?
> Suspecting the DB calls is a good first guess. The ability to log slow
> DB calls would be nice. Perhaps MySQL has something we can use here,
> assuming we log some sort of client ID on the nova-api side that we can
> use to correlate with the MySQL logs.
> External processes we run is also another place to look. Again, logging
> those processes that take longer than a certain threshold to run might
> be good.
> I'd also investigate whether it's some other greenthread blocking the
> API request thread from running. What would be really nice would be some
> way of logging when a particular greenthread ran for a long time while
> other greenthreads are pending.
> It would also be good to see some system level stats and see if it's
> just that the system is generally CPU or I/O bound while these slow
> calls are happening. Maybe logging CPU, memory, disk and network usage
> along with the top few processes every tenth of a second.
> Cheers,
> Mark.
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