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Groups > comp.lang.java.programmer > #30290
| From | Eric Sosman <esosman@comcast-dot-net.invalid> |
|---|---|
| Newsgroups | comp.lang.java.programmer |
| Subject | Re: Java 7 vs 8 speed issues on Win7? |
| Date | 2014-11-05 23:32 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <m3etjs$b9$1@dont-email.me> (permalink) |
| References | (2 earlier) <m3ditj$8bd$1@dont-email.me> <m3dus5$q4d$1@news.albasani.net> <m3ej2t$9ae$1@dont-email.me> <m3emtc$bd2$1@dont-email.me> <m3erpb$qt5$1@dont-email.me> |
On 11/5/2014 11:00 PM, Knute Johnson wrote:
> On 11/5/2014 18:37, Eric Sosman wrote:
>> On 11/5/2014 8:32 PM, Knute Johnson wrote:
>>> On 11/5/2014 11:47, Jan Burse wrote:
>>>> A fundamental change in one of the newer JDKs
>>>> is a changed semantics for substring(int, int).
>>>
>>> For better or worse?
>>
>> "Yes, probably."
>>
>> (Given the amount of data provided, that's really all the
>> answer one can offer -- and all that's deserved. C'mon, Knute:
>> No description of the application, no hint about its hot spots,
>> no profiling data, not even *one* measurement of any kind at
>> all ... How in the world can you expect useful feedback when
>> you've not fed forward?)
>>
>
> I think we are talking about two different things here.
>
> Unfortunately I can't give any good details because I was working on
> this 250 miles away with VNC. The customer had a failed computer and we
> had to get it running without any delays.
Yes, sometimes in a crisis there's no opportunity for calm
investigation. I can quite understand that; I've been in those
situations myself. Nonetheless, the complete lack of measurement
means you can't expect a diagnosis that's any better than pure
speculation. It's a casualty of the crisis.
> It is not code that was stretching the previous machine with a single
> processor running XP and Java 6 but when we configured a new computer
> with a multi-core processor, Win7 and Java 7 the code barely ran. It
> was so slow that it was no longer usable. Put in Java 8 and it is back
> to its old self, tuning along just fine. I haven't been able to
> duplicate it in my shop and we can't stop the customer's computers to
> play with them.
So, all we have is:
- An application (whose nature, function, size, and performance
characteristics aren't divulged) performed acceptably on one
machine with one O/S and one Java version,
- When the Java version, O/S, and machine were all changed, the
application performed poorly,
- When the Java version was changed yet again, things improved.
Three variables, two times two times three equals twelve configurations
of which three were observed, and the only data we have from the
observations are "it performed very poorly" and "the performance
improved considerably."
Anybody who can draw a diagnosis from so little data has psychic
powers.
> As to Jan's comments, there isn't a single call to String.substring() in
> the code anywhere and it runs fine with Java 8, so I don't think that is
> the cause. But I am still curious about what the "changed semantics"
> are and how they might impact performance.
I, too, wonder what he meant by "changed semantics," since as far
as I know the contract of String#substring(int,int) has not changed
since Java 1.0, and perhaps earlier. The underlying implementations
have changed, I believe, but that's not what I'd call a "semantic"
difference.
--
esosman@comcast-dot-net.invalid
"Don't be afraid of work. Make work afraid of you." -- TLM
Back to comp.lang.java.programmer | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
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" THAĊ˘ "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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