RE: Bytecode cache & WAS5.0

["Raikov, Leonid" <RaikovL1@xxxxxxxxx>]

Mark,

I was just unsure if the cache was being used by WAS at all; all I
wanted was to verify it was. DSPJVAPGM on the cache does work, although
in my case it only displayed the current cache size.

Lo

-----Original Message-----
From: Mark Phippard [mailto:MarkP@xxxxxxxxxxxxxxx]
Sent: 26 November 2003 18:54
To: Java Programming on and around the iSeries / AS400
Subject: RE: Bytecode cache & WAS5.0


These are the docs I am going by:

http://publib.boulder.ibm.com/iseries/v5r2/ic2924/index.htm?info/rzamy/5
0/program/clscache.htm

And this is the relevant section:

The user classloader cache improves performance in two ways:

    * Avoiding bytecode verification
      If the class is already in the cache, bytecode verification isn't 
performed again.
    * Avoiding creation of JVAPGMs
      If the class is already in the cache, the existing JVAPGM is used.

Since any optimization level can be stored in the cache, it is more 
practical to consider higher optimization levels than previously.

Note in both cases the first time the class is loaded (for example
before 
the cache is primed or after a class is changed), these functions are 
performed and the load is slower. Once the class is already in the
cache, 
these functions are not performed, so subsequent loads are much quicker.

There is no way to prime the cache with classes other than running your 
application.


So in terms of measuring performance difference to knw if it is working 
you would have to makre sure that your tests were impacted enough by
these 
two areas to show a difference.

Mark








"Raikov, Leonid" <RaikovL1@xxxxxxxxx>
Sent by: java400-l-bounces@xxxxxxxxxxxx
11/26/2003 01:37 PM
Please respond to Java Programming on and around the iSeries / AS400 
 
        To:     "'Java Programming on and around the iSeries / AS400'" 
<java400-l@xxxxxxxxxxxx>
        cc: 
        Subject:        RE: Bytecode cache & WAS5.0


 

>I do not know what you have you tried, ...

Mark

ByteCode is supposed to let you skip bytecode verification at class
loading for already compiled classes.

Lo




"Raikov, Leonid" <RaikovL1@xxxxxxxxx>
Sent by: java400-l-bounces@xxxxxxxxxxxx
11/26/2003 12:44 PM
Please respond to Java Programming on and around the iSeries / AS400

        To:     "'JAVA400-L@xxxxxxxxxxxx'" <JAVA400-L@xxxxxxxxxxxx>
        cc:
        Subject:        Bytecode cache & WAS5.0


How can I find out whether ByteCode Cache File of WAS5.0 is indeed being
used by the server? I have configured it, but since there was no visible
improvement in the response times, I can't help wondering whether the
change has actually taken place.

Lo


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