RE: Optimizing Native Java

As an example turn on log4j debug on an application based on third party 

code (String framework) yields these detailed logs and you can see 
precisely where the time goes 

Two problems with this approach. 

First. Imagine a big system (potentially, hundreds of connections and
thousands of classes) generating this type of trace. No meaningful analysis
of this data would, I'm afraid, be possible. 

Second. The time is not necessarily spent waiting for the DB server. If a
certain class is poorly implemented, it may take seconds, to, say, load a
user class from inside the "problematic" method. In order for the trace to
tell me where the problem is I have to know what I'm looking for well in
advance.

As I said, there are other tools based on the process polling principle -
same as IBM Job Watcher. They can be used while the system is in the
production mode - no debug mode is required. They (the tools) differ in the
complexity of analytical queries provided. I have my own preferences, of
course. Interestingly, it's much easier to find such tools for the iSeries
than for any other platform - mainly because Java threads map to the OS
threads under i5/OS quite nicely - at least, for the classic JVM; so to
retrieve the Java trace one has to simply use call stack retrieval APIs.

But it looks like I'm going on a tangent, so I'd better stop here and now.
:) 


Lo
 
Leonid Raikov 
Principal Consultant 
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-----Original Message-----
From: Bruce Jin [mailto:brucej@xxxxxxxxxxxxxxxxxxxx]
Sent: 17 October 2006 15:50
To: Java Programming on and around the iSeries / AS400
Subject: Re: Optimizing Native Java


As an example turn on log4j debug on an application based on third party 
code (String framework) yields these detailed logs and you can see 
precisely where the time goes 

09:37:55,750  INFO I00100a:25 - =====> I00100 starts...
09:37:55,859  INFO SqlBuilderFactory:66 - Created sql builder 
AS400/iSeries sql builder
09:37:56,250 DEBUG JdbcTemplate:299 - Executing SQL query [SELECT 
T01."EMP#",T01."LASTNAME",T01."FIRSTNAME",T01."ACTIVE",T02."DATE",T02."INCTY
PE",T02."EMPSPRVR",T02."SHIFT",T02."COWORKER",T02."INFO"  
FROM MRCJAVALIB."EMPLOYEE" T01  left outer join MRCJAVALIB."INCIDENT" 
T02 ON T01."EMP#"=T02."EMP#"    ORDER BY T01.EMP# ASC fetch first 11 
rows only]
09:37:56,250 DEBUG DataSourceUtils:106 - Fetching JDBC Connection from 
DataSource
09:37:57,437 DEBUG DataSourceUtils:272 - Returning JDBC Connection to 
DataSource
09:37:57,468 DEBUG JdbcTemplate:299 - Executing SQL query [SELECT 
COUNT(*)  FROM
09:37:58,625  INFO MrcLastRun:110 - Updated mrc dct with sql=UPDATE 
MRCJAVALIB.MRCDCT14 SET DATLST=101706,TIMESR=28 WHERE RETRN=100
09:37:58,640  INFO I00100a:137 -   -----> I00100 ends.

regards

If you and/or your third party software use a log facility (I think most 
    

software do) such as log4j you can turn on debug mode and inspect the 
log’s timestamp and see where the time goes

Easier said than done, especially for big systems. Also, as a rule,

requires

some instrumentation to be included in the application being tested.
Otherwise, only servlet/enterprise bean-level information would be

available

- personally, I find that insufficient. In any case, I certainly did not
mean that type of 3rd party software.

Lo 
________________________________________________________

Misys Banking Systems
Key West / Windsor Road / Slough / SL1 2DW

T +44 (0)1753 708 053 
M +44 (0)7903 181 030 
raikovl1@xxxxxxxxx 

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virus

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yourself. 
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-----Original Message-----
From: Bruce Jin [mailto:brucej@xxxxxxxxxxxxxxxxxxxx]
Sent: 17 October 2006 14:39
To: Java Programming on and around the iSeries / AS400
Subject: Re: Optimizing Native Java


If you and/or your third party software use a log facility (I think most 
software do) such as log4j you can turn on debug mode and inspect the 
log’s timestamp and see where the time goes

regards.

Raikov, Leonid wrote:
  

The most important thing is to understand where the time goes. Situations
when there are no bottlenecks and every class contributes to poor
performance in equal measure are pretty rare. What you need is to a)
understand what threads are primarily involved in productive work and

then

b) draw a chart describing what each of these thereads is busy doing

(e.g.

50% of the time spent waiting for JDBC queries and 50% of the time doing
    

XML
  

processing). You can hardly achieve this without Java performance

analysis

tools for System i. IBM Job Watcher is what immediately springs to mind,
    

but
  

JW data is not easy to analyse, to say the least. There are other tools,
some of them pretty good, but none of them in the Open Source domain, as
    

far
  

as I know.  

As for the magic button, there is none, I'm afraid. I would be suprised

if

memory alone could make you happy. That is, unless you're running your

JVM

in a 50MB pool.  

Lo
-----Original Message-----
From: albartell
To: 'Java Programming on and around the iSeries / AS400'
Sent: 10/16/06 4:12 PM
Subject: Optimizing Native Java

Hi All,
 
I am just completing a project where I wrote a Java proxy of sorts and
there
were a bunch of third party jar files involved in the mix. To make a
long
story short we are not satisfied with the performance we are getting out
of
the Java processes on the iSeries (note the Java is running in it's own
job
listening to a data queue - only one JVM startup).  We have run the
CRTJVAPGM against all .class and .jar files involved and are wondering
are
there any other mechanisms to look at concerning getting more speed on
the
Java end?
 
Obviously one solution would be to throw more memory at it, but is there
a
way to section off the memory so this Java process gets sole use of it
(similar to how you can do the same for Websphere Application Server)?
 
Any other idea's?
 
Aaron Bartell
New Tool! - RPG Chart Engine - visit www.mowyourlawn.com
<http://www.mowyourlawn.com/>  for more info.