Groups > comp.lang.java.programmer > #7416

Re: Style Police (a rant)

From	Lew <lewbloch@gmail.com>
Newsgroups	comp.lang.java.programmer
Subject	Re: Style Police (a rant)
Date	2011-08-27 08:34 -0700
Organization	http://groups.google.com
Message-ID	<d906c374-1751-4b85-b844-fd82569ea9ac@glegroupsg2000goo.googlegroups.com> (permalink)
References	<j39fdc$1hi$1@dont-email.me> <j3akb0$61g$1@news.albasani.net> <j3akn1$6tu$1@news.albasani.net>

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Jan Burse wrote:
>> I have noticed that final methods sometimes execute faster
>> than non-final methods. The final modifier gives a hint to
>> the optimizers.

How did you "notice" that - by what measurements under what conditions?

>> So I usually develop for a while without bothering about final,
>> then I run some of the style checks of the IDA, that also spot
>> missing final keywords. And I put the final keywords.
> 
> The final keywords is found more then ten time (>10) on
> the following page:
> http://www.javaperformancetuning.com/tips/rawtips.shtml

Really? You're citing performance optimization tips from 1999-2991?

You do realize that virtually no performance "tips" from that era apply any more, right?

Even in 2002 the use of 'final' to help optimize was recognized as urban legend:
http://www.ibm.com/developerworks/java/library/j-jtp1029/index.html
"Like many myths about Java performance, the erroneous belief that declaring classes or methods as final results in better performance is widely held but rarely examined. The argument goes that declaring a method or class as final means that the compiler can inline method calls more aggressively, because it knows that at run time this is definitely the version of the method that's going to be called. But this is simply not true. Just because class X is compiled against final class Y doesn't mean that the same version of class Y will be loaded at run time. So the compiler cannot inline such cross-class method calls safely, final or not. Only if a method is private can the compiler inline it freely, and in that case, the final keyword would be redundant.

"On the other hand, the run-time environment and JIT compiler have more information about what classes are actually loaded, and can make much better optimization decisions than the compiler can. If the run-time environment knows that no classes are loaded that extend Y, then it can safely inline calls to methods of Y, regardless of whether Y is final (as long as it can invalidate such JIT-compiled code if a subclass of Y is later loaded). So the reality is that while final might be a useful hint to a dumb run-time optimizer that doesn't perform any global dependency analysis, its use doesn't actually enable very many compile-time optimizations, and is not needed by a smart JIT to perform run-time optimizations."

-- 
Lew

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Thread

Style Police (a rant) Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-26 20:56 -0400
  Re: Style Police (a rant) Robert Klemme <shortcutter@googlemail.com> - 2011-08-27 09:58 +0200
  Re: Style Police (a rant) Rajiv Gupta <rajiv@invalid.com> - 2011-08-27 18:02 +1000
    Re: Style Police (a rant) v_borchert@despammed.com (Volker Borchert) - 2011-08-27 08:40 +0000
  Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-27 13:27 +0200
    Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-27 13:33 +0200
      Re: Style Police (a rant) Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-27 11:08 -0400
      Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-27 08:34 -0700
        Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-27 08:37 -0700
        Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-27 17:59 +0200
          Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-27 18:06 +0200
            Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-27 18:08 +0200
            Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-27 09:50 -0700
              Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-27 19:15 +0200
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-27 13:09 -0700
                Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-27 23:18 +0200
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-27 16:10 -0700
                Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-28 01:59 +0200
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-27 18:59 -0700
                Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-28 15:32 +0200
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-28 13:09 -0700
                Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-29 04:02 +0200
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-28 19:20 -0700
                Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-29 09:44 +0200
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-29 08:30 -0700
                Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-29 16:37 +0000
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-29 12:10 -0700
                Re: Style Police (a rant) Robert Klemme <shortcutter@googlemail.com> - 2011-08-29 18:21 +0200
                Re: Style Police (a rant) Jan Burse <janburse@fastmail.fm> - 2011-08-29 04:06 +0200
    Re: Style Police (a rant) Wanja Gayk <brixomatic@yahoo.com> - 2011-09-10 06:45 +0200
      Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-10 11:40 +0000
        Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-09-10 14:06 -0700
          Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-11 14:07 +0000
            Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 10:55 -0400
              Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-11 23:34 +0000
            Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 10:58 -0400
              Re: Style Police (a rant) Patricia Shanahan <pats@acm.org> - 2011-09-11 10:12 -0700
            Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-09-11 09:47 -0700
              Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-11 23:32 +0000
            Re: Style Police (a rant) Wanja Gayk <brixomatic@yahoo.com> - 2011-09-11 21:20 +0200
              Re: Style Police (a rant) Cthun <cthun_117@qmail.net.au> - 2011-09-11 17:11 -0400
                Re: Style Police (a rant) Wanja Gayk <brixomatic@yahoo.com> - 2011-09-12 01:22 +0200
                Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 21:13 -0400
                Re: Style Police (a rant) Retahiv Oopsiscame <roopsisc@gmail.com> - 2011-09-11 16:54 -0700
                Re: Style Police (a rant) Cthun <cthun_117@qmail.net.au> - 2011-09-11 23:42 -0400
                Re: Style Police (a rant) "Cthun" <cthun_117@qmail.net.au> - 2011-09-12 04:56 -0400
                Re: Style Police (a rant) Cthun <cthun_117@qmail.net.au> - 2011-09-12 05:12 -0400
                Re: Style Police (a rant) "Cthun" <cthun_117@qmail.net.au> - 2011-09-12 04:59 -0400
                Re: Style Police (a rant) Cthun <cthun_117@qmail.net.au> - 2011-09-12 05:13 -0400
              Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-11 23:17 +0000
                Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 21:12 -0400
                Re: Style Police (a rant) Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-09-12 07:36 -0300
              Re: Style Police (a rant) "Cthun" <cthun_117@qmail.net.au> - 2011-09-12 04:58 -0400
                Re: Style Police (a rant) Cthun <cthun_117@qmail.net.au> - 2011-09-12 05:12 -0400
        Re: Style Police (a rant) Wanja Gayk <brixomatic@yahoo.com> - 2011-09-11 15:33 +0200
          Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-09-11 09:42 -0700
            Re: Style Police (a rant) Lars Enderin <lars.enderin@telia.com> - 2011-09-11 20:35 +0200
              Re: Style Police (a rant) Retahiv Oopsiscame <roopsisc@gmail.com> - 2011-09-11 16:55 -0700
                Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-09-11 20:36 -0700
                Re: Style Police (a rant) Lars Enderin <lars.enderin@telia.com> - 2011-09-12 10:05 +0200
                Re: Style Police (a rant) "Cthun" <cthun_117@qmail.net.au> - 2011-09-12 04:52 -0400
                Re: Style Police (a rant) Cthun <cthun_117@qmail.net.au> - 2011-09-12 05:14 -0400
                Re: Style Police (a rant) "Cthun" <cthun_117@qmail.net.au> - 2011-09-12 06:42 -0400
                Re: Style Police (a rant) Cthun <cthun_117@qmail.net.au> - 2011-09-12 07:20 -0400
                Re: Style Police (a rant) "Cthun" <cthun_117@qmail.net.au> - 2011-09-12 08:46 -0400
              Re: Style Police (a rant) Tom Anderson <twic@urchin.earth.li> - 2011-09-12 20:18 +0100
            Re: Style Police (a rant) Wanja Gayk <brixomatic@yahoo.com> - 2011-09-11 21:20 +0200
              Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-09-11 13:52 -0700
          Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-12 00:17 +0000
      Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-10 21:32 -0400
        Re: Style Police (a rant) Wanja Gayk <brixomatic@yahoo.com> - 2011-09-11 13:27 +0200
          Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 11:05 -0400
        Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-11 13:23 +0000
          Re: Style Police (a rant) Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-09-11 10:04 -0400
            Re: Style Police (a rant) Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-09-11 12:45 -0300
              Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 16:53 -0400
          Re: Style Police (a rant) Arne Vajhøj <arne@vajhoej.dk> - 2011-09-11 10:59 -0400
            Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-09-11 21:25 +0000
  Re: Style Police (a rant) Tom Anderson <twic@urchin.earth.li> - 2011-08-27 14:00 +0100
    Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-27 08:42 -0700
    Re: Style Police (a rant) Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-27 11:58 -0400
  Re: Style Police (a rant) "John B. Matthews" <nospam@nospam.invalid> - 2011-08-28 08:21 -0400
    Re: Style Police (a rant) Arved Sandstrom <asandstrom3minus1@eastlink.ca> - 2011-08-28 18:07 -0300
  Re: Style Police (a rant) Roedy Green <see_website@mindprod.com.invalid> - 2011-08-29 04:20 -0700
  Re: Style Police (a rant) Tim Slattery <Slattery_T@bls.gov> - 2011-08-29 09:11 -0400
    Re: Style Police (a rant) Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-08-29 20:50 -0400
      Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-30 11:27 +0000
        Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-30 09:36 -0700
          Re: Style Police (a rant) Andreas Leitgeb <avl@gamma.logic.tuwien.ac.at> - 2011-08-30 17:51 +0000
      Re: Style Police (a rant) Tim Slattery <Slattery_T@bls.gov> - 2011-08-30 08:51 -0400
      Re: Style Police (a rant) Patricia Shanahan <pats@acm.org> - 2011-08-30 09:04 -0700
        Re: Style Police (a rant) Lew <lewbloch@gmail.com> - 2011-08-30 09:43 -0700
          Re: Style Police (a rant) Daniele Futtorovic <da.futt.news@laposte-dot-net.invalid> - 2011-08-31 00:31 +0200

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