On Mar 4, 2010, at 12:41 PM, David Blevins wrote: > Started looking into how we might finally get some Monitoring support into > the code. Basic stats and the like viewable via JMX or something similar. > > Still very much in the research phase of all that. If anyone has done any > work in that area, I'm interested in some tips. Or if anyone has been on the > "user" side of consuming stats and has some "loves" and "hates" to share, > that's also great info -- hopefully our impl would stick close to the loves > and steer clear of the hates. > > And of course, if there are specific stats that anyone would like, definitely > feel encouraged to speak up. No reason we can't put those higher in the > priority list.
Been back at this one the last two weeks. Have some pretty neat code in so far. I started with a copy of Martin Traverso's (an Apache guy) tiny jmxutil code which scans objects for @Managed annotated methods and creates a ModelMBean based on those methods. The more I started writing actual stats though, the less I liked the ModelMBean approach as it can only handle methods which then requires a lot of pointless getters just for the JMX tooling. ModelMBeans are also pretty rigid in that one object == one mbean, so it isn't possible to "roll up" attributes in to one basic MBean if those attributes are methods of different java objects. I'm not a fan of having internal code structure exposed to users when in most cases it doesn't benefit them and simply subjects them to more brittle finer views: do users care that in my Pool object I have a "stats" object and in that object there are other "stats" objects and do they really need an individual MBean for each and every one of these fine grained objects? No, of course not. What makes my life easy as a developer, doesn't always make their lives easy as a user. Anyway, so I wrote my own little annotation based JMX exporter. You pass in an object that has fields and/or methods annotated with @Managed. It will inspect all those fields/methods and if any of them are types that also are marked @Managed, it will walk down those types and collect its fields/methods. So it's a basic recursive tree walk, starting with the root object, that rolls up everything it finds as one flat list of JMX attributes. It also allows these fields/methods to be private in scope, so it isn't necessary to "dirty" your design to get complete stats. The result is something exposes a nice clean view like this one: https://issues.apache.org/jira/secure/attachment/12443866/jmx-monitoring.png That's the view of our stateless pool stats via JConsole. Still have a few "wires" to hookup, but it's looking good. Next part will be getting stats for each method invocation on a bean. Comments welcome! :) -David
