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

["Xu, Weining" <Weining.Xu@xxxxxxx>]

one more thing you could look at....

Check AS400 system pool size memory by command WRKSYSSTS.  Find out which
system pool your Java job is running.  If you use SBMJOB CMD(RUNJVA .....)
to invoke Java program, the job should be in QBATCH subsystem. If the Pool
Size for QBATCH is set too low, your Java program would be very slow.

My example...
I have a Java program that was very very slow on AS400 a few month ago.
Then I found out that there is only 20MB pool size alocated in QBATCH
subsystem.  After increased that size to 120 MB, my program running time
reduced from 8 hrs to 2 hrs.

-----Original Message-----
From: Hall, Philip [mailto:phall@spss.com]
Sent: Friday, May 24, 2002 10:16 AM
To: java400-l@midrange.com
Subject: RE: Very Slow Run Time on AS/400 for Java Program



Hello,

> PreparedStatement pstmt_select = ca.prepareStatement
>     ("SELECT LWHS, LLOC, LPROD, LLOT, (LOPB - LISSU + LADJU + LRCT -
> LIALOC), LOPB, LISSU, LADJU, LRCT, LIALOC FROM " +
> as400Library + ".ILI");

One thing I have noticed, contrary to the normal belief, is that prepared
statements are some times slower than re-building the SQL statement.

One recent project on Windows2K using SQL7, individual "insert into's" where
10x *faster* than using a prepared statement and I was just changing the
data. I was testing as we had records to add to the same table (about 20 odd
fields) and in this case a prepared statement was worse.

I finally implemented it using bulk loading, which is lightening fast...

108000 records
-  prepared statement takes about forever
-  individual inserts takes about 7 mins
-  bulk loading takes about just over a minute

--phil
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