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RE: OC4J Process Architecture

From: Adrian Turner <>
Date: Mon, 14 Jun 2004 20:31:52 +0100
Message-ID: <>

Hi Jurijs,

OC4J started out life as the Orion Application Server. Check out as there is a doc library there which is likely still valid.

A good approach seems to be to build a repeatable install process using the automation tools (dcmctl and admin.jar). If you get a problem take a slash/burn/rebuild approach to the whole installation; this seems to solve a lot of corruption issues.

After that, if you still get problems, do what we have and pay to have a technically current Oracle Corporation consultant onsite. A good one can pretty much spot a bug 50 hours before support will. His approach is normally to reverse engineer the code from the JAR files (actually anyone can), check the problem out himself and then tell support what needs fixing. At least you will know what you are dealing with if you can see the code.

Kind Regards,

  -----Original Message-----
[]On Behalf Of   Sent: 13 June 2004 18:05
  Subject: OC4J Process Architecture

  OC4J Process Architecture

  1 year ago, management of the company I am working for decided to switch all development projects to J2EE architecture (OC4J).

  Within the year, we have running in many technical problems connected to OC4J (stability hanging, java deadlocks, performance problems etc). We have logged many (~10) long (100KB of text, 2-4 mount) TARs to Oracle support. Generally there no many help from Oracle side. I have filling there no strong competence from Oracle analystís side ;(

  We have learned a lot about OC4J architecture, parameters etc. during this time (see information below). But at the moment I still have filling that we are working in the dark, using black box method.

  I will try to explain that I mean, by comparing Oracle Database & Oracle OC4J.
  There excellent documentation regarding Oracle Database architecture (Oracle Concepts). There is good description about each Database process PMON, SMON, etc, there is one process per connection (in dedicated configuration), there is many diagnostic possibilities etc. If I have performance issue with Oracle Database, first of all I will take a look on TOP CPU consumers from OS respective, then Iíll go forward to Oracle statistics or switching 10046 event etc.

  As opposite, take a look on OC4J. There is no any information like mentioned above regarding OC4J, not in Oracle documentation, not in the Web ;(. There is just one process, which represent OC4J from OS. If there is performance issue with OC4J, we canít say a lot regarding which process/activity/piece of code takes CPU etc.

  My question is:

  Thank you in advance,

  I would like to share information that we have regarding OC4J architecture (see below).

  As I mentioned above OC4J from OS looks like one process, which consume HW resources. OC4J use threads architecture for endow concurrency. You can see threads dump in the Java output (in $OH opmn/logs/<component name>.default_island.1 log file by default) by running   a)
  kill Ė3 <oc4j pid>
  command (this is any java process behavior, I believe).   From dump we can see main threads list, as well as information about java deadlocks if any.
  b) Below is thread types list you can see in the java output by running kill Ė3 command:
  AJPConnectionListener []   ApplicationServerThread-0
  Reference Handler
  RMIServer [] count:2   Signal Dispatcher
  Suspend Checker Thread
  VM Periodic Task Thread
  VM Thread
  Unfortunately I donít have information about algorithms of work and what is responsibility of each type of thread, at the moment.   c) In addition there is garbage collector process.   There is many information in the Web regarding this type of process.   For example
  -verbose:gc parameter usage is helpful in diagnostic process.

  II. The TOP parameters you need to look on is:   a)
  File $OH/opmn/conf/opmn.xml

  <java-option value="-Xms1024M -Xmx1024M "/>
  <log-file path="$OH//opmn/logs/ipm.log" level="3"/>
  <log-file path="$OH/opmn/logs/ons.log" level="3"/>
  File $OH/j2ee/<component name>/config/server.xml   <global-thread-pool min="100" max="200" queue="120" keepAlive="600000" cx-min="100" cx-max="200" cx-que ue="120" cx-keepAlive="600000" debug="true" />
  transaction-config timeout="500000"
  File $OH/j2ee/<component name>/config/   If you use BC4J.

  Hope this information will help you.

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Received on Mon Jun 14 2004 - 14:32:19 CDT

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