Sampling Rate

[lashford]

We need to add a sampling rate to the pointcuts advices so to lower the performance hit on the monitored system.

The sampling rate needs to be configurable for:

• actor selection using full actor path (akka://default/user/supervisor/$a)
• actor selection using wildcard path, where * is any path element, .. is any path elements (akka://default/../supervisor)
• actor selection using full actor type (akka:default.org.eignego.actors.FooActor or akka:*.org.eigengo.actors.FooActor, where * is any actor system name)
• actor selection using wildcard actor type (akka:default._ :> org.eigengo.actors.FooActor)

The last point's syntax is arguably a bit hairy. It follows the Scala syntax, but we can also go for the AspectJ-style syntax: akka:default.org.eigengo.actors.FooActor+.

[janm399]

Imagine

org.eigengo.monitor.agent {
    output {
        class: "org.eigengo.monitor.TestCounterInterface"
    }


    akka {
        included: [ "akka://default/user/foo", "akka.*.some.Foo" ]
        excluded: [ "akka://default/user/bar", "akka.*.some.Baz" ]

        sampling {
          rate: 5
          for: [ "akka://default/user/special"]
        }

        sampling {
          rate: 15
          for: [ "akka://default/user/baz"]
        }
    }
}

[janm399]

This will also require state in the aspect: a map of JoinPoint + actor path => invocation count. If count % sampling == 0 then send to DD

However, remember that this will require some serious testing of race conditions.

[hughsimpson]

#56 for sampling rate