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Re: Java 7 vs 8 speed issues on Win7?

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Eric Sosman schrieb:
>
>      However, the correction leaves me wondering just what *does*
> constitute a "semantic" change, in your estimation.  On the one
> hand you maintain that a change in the `private' behavior of
> String is a "semantic" change, although its only externally-
> visible effect is on performance, not on function.  On the other,
> you hold that a hypothetical change to `switch' would *not* be a
> "semantic" change, since it only affects performance but does not
> change the outcome.  I cannot see what distinguishes the two cases,
> why one function-preserving-but-performance-altering change is
> "semantic" and the other is not.

Typically a compiler optimization leads to a better
non-functional result, which is not considered a semantic
change, although it is. On the other hand what happend
with String.substring did degenerate the performance
in many cases. So it gets a different attention.

That there is probably problem a in being precise in
non-functional requirements has already been recognized.
Here is a particular example, in a 10 years framework.
You see the initial conception of this here:

Research Abstract: Semantic Concepts for the Specification of 
Non-functional Properties of Component-Based Software
by Steffen Zschaler

I guess it is from 2002. And it begins with:

	"The area of semantics for functional specifications has been well 
understood for quite a long time already. In contrast, for 
non-functional specifications there exists—to the best of my 
knowledge—no commonly accepted understanding of what constitutes a 
definition of semantics. Various specialized approaches can be found in 
the literature (e.g., [10, 7, 8]), but they are either incomplete or 
very domain specific. Secondly, component-based software development 
[11] is an important trend in software engineering. Its main promises 
are reusability and exchangeability of components in a system. Both are 
achieved through a principle of locality: Every component needs to 
explicitly specify what services it provides and what it needs in order 
to provide."

http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.148.6537

Then later, actually more then 10 years later one finds:

On the Reusable Specification of Non-functional
Properties in DSLs

	"In this paper, we discuss how such building blocks can
be constructed for the specification and analysis
of a range of non-functional properties, such as,
for example, throughput, response time, or reliability
properties. We assume DSL semantics to be provided
through a set of transformation rules, which enables a
range of analyses based on model checking."

http://www.steffen-zschaler.de/publications/sle2012.pdf

Looks like things have gotten even more complex. To
formally make accessible non functional requirements
in Java, I would probably use the Java annontation
mechanism. And what we would see for substring(int,int)
would be that the corresponding annotation would
change, and warn us about that now char[] is copied,

but for a better switch statement, a better
compilation I wouldn't know where to lookup
this annotation. And even if the Hotspot JVM can
do it, probably my Dalvik JVM will not do it, to
conserve battery life, it will do no JITing
at all.

Bye

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Java 7 vs 8 speed issues on Win7? Knute Johnson <eternal@knutejohnson.com> - 2014-10-22 10:18 -0700
  Re: Java 7 vs 8 speed issues on Win7? Silvio <silvio@internet.com> - 2014-10-24 11:10 +0200
  Re: Java 7 vs 8 speed issues on Win7? Roedy Green <see_website@mindprod.com.invalid> - 2014-11-05 04:36 -0800
    Re: Java 7 vs 8 speed issues on Win7? Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2014-11-05 08:23 -0800
      Re: Java 7 vs 8 speed issues on Win7? Jan Burse <janburse@fastmail.fm> - 2014-11-05 20:47 +0100
        Re: Java 7 vs 8 speed issues on Win7? Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2014-11-05 17:32 -0800
          Re: Java 7 vs 8 speed issues on Win7? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-05 21:37 -0500
            Re: Java 7 vs 8 speed issues on Win7? Knute Johnson <nospam@rabbitbrush.frazmtn.com> - 2014-11-05 20:00 -0800
              Re: Java 7 vs 8 speed issues on Win7? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-05 23:32 -0500
                Re: Java 7 vs 8 speed issues on Win7? Robert Klemme <shortcutter@googlemail.com> - 2014-11-06 08:48 +0100
                Re: Java 7 vs 8 speed issues on Win7? Jan Burse <janburse@fastmail.fm> - 2014-11-06 15:09 +0100
                Re: Java 7 vs 8 speed issues on Win7? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-06 09:50 -0500
                Re: Java 7 vs 8 speed issues on Win7? Jan Burse <janburse@fastmail.fm> - 2014-11-06 18:21 +0100
                Re: Java 7 vs 8 speed issues on Win7? Jan Burse <janburse@fastmail.fm> - 2014-11-06 18:34 +0100
                Re: Java 7 vs 8 speed issues on Win7? Jan Burse <janburse@fastmail.fm> - 2014-11-06 23:03 +0100
                Re: Java 7 vs 8 speed issues on Win7? Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-06 17:21 -0500
                Re: Java 7 vs 8 speed issues on Win7? Jan Burse <janburse@fastmail.fm> - 2014-11-07 00:07 +0100
                Re: Java 7 vs 8 speed issues on Win7? "Bob(but not" THAŢ "Bob)" <nobody@nowhere.net> - 2014-11-07 08:48 +0000
                Re: Java 7 vs 8 speed issues on Win7? Jan Burse <janburse@fastmail.fm> - 2014-11-08 11:28 +0100
        Re: Java 7 vs 8 speed issues on Win7? Roedy Green <see_website@mindprod.com.invalid> - 2014-11-20 03:12 -0800
          Re: Java 7 vs 8 speed issues on Win7? Silvio <silvio@internet.com> - 2014-11-20 13:24 +0100
            Re: Java 7 vs 8 speed issues on Win7? Robert Klemme <shortcutter@googlemail.com> - 2014-11-20 19:06 +0100
              Re: Java 7 vs 8 speed issues on Win7? Silvio <silvio@internet.com> - 2014-11-20 22:54 +0100
                Re: Java 7 vs 8 speed issues on Win7? Brixomatic <brixomatic@yahoo.com> - 2014-11-22 08:54 +0100
                Re: Java 7 vs 8 speed issues on Win7? Brixomatic <brixomatic@yahoo.com> - 2014-11-22 09:19 +0100
    Re: Java 7 vs 8 speed issues on Win7? Fredrik Jonson <fredrik@jonson.org> - 2014-11-29 07:44 +0000

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