Re: Very Slow Run Time on AS/400 for Java Program

How big is your iSeries (both processor and memory)?  Java uses a lot of
memory so maybe your box is memory constrained.  You seem to be doing the
right things.  CRTJVAPGM makes a big difference on v4r5 machines but you
already did that.

Also, not that it will help performance, but you mentioned jt400.jar.  If
you are using the native JDBC driver you don't need that jar in your
classpath (unless you are using some other Toolbox class).

David Wall
Toolbox for Java
iSeries ODBC Driver for Linux




                      Joyce Louie
                      <JLouie@Haemoneti        To:       
"'java400-l@midrange.com'" <java400-l@midrange.com>
                      cs.com>                  cc:
                      Sent by:                 Subject:  Very Slow Run Time on 
AS/400 for Java Program
                      java400-l-admin@m
                      idrange.com


                      05/22/2002 12:36
                      PM
                      Please respond to
                      java400-l





Hi,

I put my question out on JGuru but got no replies so hopefully you can help
me out here.  I wrote a Java program to Select records (by certain fields)
from an AS/400 file, Delete from an Sql Server table, and then Insert the
selected records to this Sql Server table.
My environment is:  OS/400 V4R5, JDK 1.3, Native JDBC driver (from AS/400
Developer Kit for Java).  I am using the latest versions of the db2_classes
(AS/400), and msbase, msutil and mssqlserver (MS Sql Server) jar files in
my
classpath.  I used QSH javac to create the class for my Java program.  I
then did a CRTJVAPGM at optimization=40 for this class, as well as the 3 MS
Sql Server jar files (I got "unable to create" error when I tried the
CRTJVAPGM on the AS/400 jar file).  I am using blocked fetch (set the block
size to 570, which is a multiple of the total length of my fields), and
batch update (using addBatch and executeBatch instead of executeUpdate in
my
results loop) - both of these coding logic were ones that I found in a JDBC
performance tips document.
The problem is that  the Java program runs VERY slowly on the AS/400
(either
from QSH with java, or with RUNJVA) and uses up alot of CPU resources.  It
runs well over 10 times longer than if I ran it from the PC DOC
environment.
Any suggestions on what could be causing such poor performance when running
the Java program on the AS/400?  I have scanned many Java/400 forums and
websites but am just about out of ideas on what to try next.  My Java
program is virtually useless the way it runs now on the AS/400.  Please
help!
Thanks alot!



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