[Mulgara-dev] Monitoring resource use

[Life is hard, and then you die]

On Fri, Nov 07, 2008 at 05:37:49PM -0500, Alex Hall wrote:
> Does anybody have any insight into the topic of monitoring resource
> usage of a Mulgara server?  The idea is, once we put up a publicly
> available, Mulgara-backed website that incorporates the ability to
> execute SPARQL queries, we expose ourselves to denial-of-service
> attacks.  The sort of thing that I would be interested in doing is
> some sort of throttling or rate control; assigning different
> priorities to queries; and monitoring queries to either kill or
> lower the priority of ones that are running too long.  One possible
> approach would be to extend MBean capability to the Session level
> (right now there is an MBean interface for the server object) but
> I'm sure there are others.  I'd love to hear back from anybody with
> experience or thoughts on this topic.

Right we just monitor by looking at os stats such as cpu and memory
used; more JMX support would be really great, though (there is the
ServerMBean, but it's not actually exported as an MBean).

Regarding throttling etc, I'm not sure how you want to achieve that
within mulgara, unless you start getting really intrusive and add
things like explicit sleep()'s and checks all over. You can't rely on
thread priorities in Java, btw, (e.g. they're wholly ignored on Linux)
and even if they're implemented I don't think they'll do much as soon
as you're disk IO bound.


  Cheers,

  Ronald