Re: [Vtd-xml-users] Storing parsing info

[Jimmy Z. <cra...@co...>]

Tatu, Are you aware of any pointers that discusses the behavior for server
 JVM a bit more... In addition to your suggestion, I also think that the 
behavior
of JVM has to do with file sizes as well... for a large GML, JVM seems to 
reach
steady state (native code) pretty quickly...
Jimmy
----- Original Message ----- 
From: "Tatu Saloranta" <cow...@ya...>
To: "Fernando Gonzalez" <fer...@gm...>; 
<vtd...@li...>
Sent: Monday, March 19, 2007 12:19 PM
Subject: Re: [Vtd-xml-users] Storing parsing info


>
> --- Fernando Gonzalez <fer...@gm...> wrote:
>
>> Well, jeje, the computer is new but I don't think my
>> disk is so fast. I
>> think Java or the operating system has to cache
>> something because the first
>> time I load the file it takes a bit more than 2
>> seconds and after the first
>> load, it only takes 300ms to read the file...
>> I have no experience on doing benchmarks and maybe
>> I'm am missing something.
>> That's why I attached the program.
>
> One thing you need to know is that JVM's HotSpot does
> incremental optimization. As such, calling anything
> first time (or, rather, first N, where N can be like
> 2000 times) will take much much longer. This because
> code at first will be interpreted from byte code. Only
> after JVM notices particular part code is so-called
> "hot spot" (called so often it is where most time is
> spent) it will inline it to native code.
>
> Because of this, one must always ensure that there is
> enough of so-called warmup time to reach steady state
> performance. That is, unless your use case is such
> where you only run things once, using separate JVM
> instance.
>
> So it perfectly normal (and expected) that
> loading+parsing things first time is significantly
> slower than second time around.
> If you want to ensure it's not due to OS-level disk
> block caching (which also affects results), you can
> warm things up using different xml files: code paths
> should be same or similar, so HotSpot will optimize
> code, but data is different, so OS won't be able to
> cache it.
>
> Hope this helps,
>
> -+ Tatu +-
>
>
>
>
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