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Re: method micro benachmarking with reflection

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On 7/30/2015 6:41 AM, philipp.kraus.flashpixx@gmail.com wrote:
> Hello,
>
> I have got a complex system and I would like to add some microbenchmarks to the application.
> So I need the runtime of a method call, but I don't want to add to each method a time counter. Can I add via reflection API a structure, that adds the micro benchmarks automatically? E.g.
>
> registerbenchmark( myclass.class, mymethod-handle ).
>
> This calls should do on any object
>
> myclass x = new myclass();
>
> timer start
> x.mymethod();
> timer stop
>
> So I would like to do register all classes & methods on the application startup and on any instance of a class the benchmark code should be run. So I need an event, which is called on each method call.
>
> Can I register an event-handler at the JVM to get each method call? Does there exists some frameworks for microbenchmarking?

     (Disclaimer: I've never done this ...)

     I think that java.lang.instrument package can be used for this
sort of thing.  It lets you change a method's byte code on the fly,
so you can insert calls to start and stop timers or whatever.

     BUT: Unless a method has "macroscopic" run time, you'll have a
hard time finding a sufficiently fine-grained timer.  Nothing Java
itself supplies will suffice (System.nanoTime() may look promising,
but even though it gives a result in nanoseconds it seldom measures
that precisely).  Using JNI, you might be able to access chip-specific
low-level cycle counters or some such -- but even then, you'd have to
take it on faith that all the cycles between a method's start and end
were consumed by the method; what if the garbage collector decided to
preempt the method's thread for a few milliseconds?

     Final thought: Re-read the disclaimer ...

-- 
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM

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method micro benachmarking with reflection philipp.kraus.flashpixx@gmail.com - 2015-07-30 03:41 -0700
  Re: method micro benachmarking with reflection Arne Vajhøj <arne@vajhoej.dk> - 2015-07-30 07:16 -0400
    Re: method micro benachmarking with reflection Arne Vajhøj <arne@vajhoej.dk> - 2015-07-30 21:52 -0400
      Re: method micro benachmarking with reflection Arne Vajhøj <arne@vajhoej.dk> - 2015-07-30 21:55 -0400
  Re: method micro benachmarking with reflection Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-30 08:23 -0400
    Re: method micro benachmarking with reflection e.d.programmer@gmail.com - 2015-07-30 06:00 -0700
      Re: method micro benachmarking with reflection Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-30 09:30 -0400
        Re: method micro benachmarking with reflection e.d.programmer@gmail.com - 2015-07-30 08:26 -0700
          Re: method micro benachmarking with reflection Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-30 11:42 -0400
            Re: method micro benachmarking with reflection e.d.programmer@gmail.com - 2015-07-30 10:30 -0700
              Re: method micro benachmarking with reflection Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-30 14:20 -0400
        Re: method micro benachmarking with reflection Jeff Higgins <jeff@invalid.invalid> - 2015-07-30 16:08 -0400
    Re: method micro benachmarking with reflection philipp.kraus.flashpixx@gmail.com - 2015-07-30 06:11 -0700
    Re: method micro benachmarking with reflection v_borchert@despammed.com (Volker Borchert) - 2015-07-30 21:33 +0000
      Re: method micro benachmarking with reflection Eric Sosman <esosman@comcast-dot-net.invalid> - 2015-07-30 18:18 -0400
        Re: method micro benachmarking with reflection Arne Vajhøj <arne@vajhoej.dk> - 2015-07-30 20:13 -0400
  Re: method micro benachmarking with reflection Jeff Higgins <jeff@invalid.invalid> - 2015-07-30 17:11 -0400
  Re: method micro benachmarking with reflection v_borchert@despammed.com (Volker Borchert) - 2015-07-30 21:53 +0000
  Re: method micro benachmarking with reflection Sebastian <news@seyweiler.dyndns.org> - 2015-08-04 21:44 +0200

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