Path: csiph.com!optima2.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!1.eu.feeder.erje.net!eternal-september.org!feeder.eternal-september.org!mx02.eternal-september.org!.POSTED!not-for-mail From: Eric Sosman Newsgroups: comp.lang.java.programmer Subject: Re: method micro benachmarking with reflection Date: Thu, 30 Jul 2015 08:23:39 -0400 Organization: A noiseless patient Spider Lines: 41 Message-ID: References: <7c2ab94b-ee4e-41c9-ae71-3896210e80b7@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Thu, 30 Jul 2015 12:22:11 +0000 (UTC) Injection-Info: mx02.eternal-september.org; posting-host="858a9d65d95f4ea4d355bd116aa2cdbf"; logging-data="4442"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1/b/MKuAgoi6X6qVDRB9mA3" User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.1.0 In-Reply-To: <7c2ab94b-ee4e-41c9-ae71-3896210e80b7@googlegroups.com> Cancel-Lock: sha1:C/sk2nSjE/Qz7MyccuU7LQSWJyA= Xref: csiph.com comp.lang.java.programmer:32208 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