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Posted by Lew on 11/14/07 20:10
Daniel Dyer wrote:
> On Wed, 14 Nov 2007 19:13:30 -0000, Steve <no.one@example.com> wrote:
>
>>
>> "Wojtek" <nowhere@a.com> wrote in message
>> news:mn.727b7d7b87640b69.70216@a.com...
>>> Steve wrote :
>>>> php and java only get ONE pass at doing an optimization.
>>>
>>> Nope. Modern Java implementations use adaptive optimization during
>>> runtime. With traditional compiled languages, the compiler does it once.
>>>
>>> http://en.wikipedia.org/wiki/Java_performance#Adaptive_optimization
>>
>> what i'm saying is that this is not a continual process, like a gui, or
>> running process on a system. in the context of the web, java doesn't
>> get to
>> capitalize on more than a few adaptations given the
>> run-produce-output-and-done nature of a web hit. make sense?
>>
>
> No, because the JVM's optimisation is over the lifetime of the JVM not
> the liftime of a single request. A request just invokes a method in a
> pre-existing Java application. That single, long-running Java
> application is the servlet container (something like Tomcat or Jetty).
> The container can either run standalone and serve-up everything
> (including HTML and static resources) or, more common in large systems,
> it can sit behind Apache, which will serve the static content and defer
> to the servlet container for dynamic content.
>
> So the JIT compiler can (and does) use information it has gathered from
> hundreds or thousands of hits over hours or days in order to optimise
> the code.
Steve,
Check out the white papers and articles on JVMs and how they optimize code.
--
Lew
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