True, knew I was going to get myself into trouble answering this one :)
Still believe that using ValueObjects and a Distributed Facade is a better
way to go. In many cases your web container & EJB container are not running
on the same machine in production.
However because both are in VM in this case then network traffic is not an
issue.
Could it be that the entity beans are causing the ejbStore() method to fire
for each attribute that is retrieved from them because of container managed
transactions ?
Maybe Saul could stick some System.outs in his ejbLoad() & ejbStore()
methods to see what is happening.
Jonathan
-----Original Message-----
From: marc fleury [mailto:[EMAIL PROTECTED]]
Sent: Thursday, 5 July 2001 2:55 p.m.
To: [EMAIL PROTECTED]
Subject: RE: [JBoss-user] JBoss performance problems
|1) You do a network call for home look up
|2) You do a network call for the findAll(), the server returns the
|enumeration
|3) You do a network call to get an attribute from the entity bean
|3a) The server starts a transaction
|3b) server gets attributes from ejb
|3c) The server commits the transaction (which can result in a DB update
|unless you are using dirty flags)
|3d) Server returns value to client (more network traffic)
|4) You repeat step 3 for each attributes you fetch
|5) You repeat step 4 for each row
? we are integrated in VM with jetty and tomcat
marcf
|
|Also if this is the first time you have accessed these entity beans, the
|server will have to create and data fill them from the database.
|
|As you can see above, you are doing a large number of network calls which
|are expensive & a large number of transactions which is even more
|expensive.
|
|A better approach is to use stateless session beans as Facades for your
|entity beans. The session bean talks to your entity beans, data fills a
|serializable class (a ValueObject) with the data for each row and
|returns an
|array or collection of these back to the client.
|
|If you do that the client/server flow looks like:
|
|1) You do a network call for home look up for your session bean
|2) You do a network call to the home calling create() to get the remote
|interface
|3) You do a network call to your session bean calling a getRows() method
|3a) Server starts a transaction
|3b) Session bean lookups the home of the your entity bean (usually a
|optimised call since we are in the container already)
|3c) Session bean calls findAll() on the entity bean's home and gets an
|enumeration of entity beans
|3d) Session bean creates a collection
|3e) Session bean creates a ValueObject and copies the attributes from the
|entity bean to the ValeuObject. (Once again these calls are optimised
|because we are in container already)
|3f) Session bean adds ValueObject to the collection
|3g) Steps 3e, 3f are repeated for each row (entity bean)
|3h) Session bean returns collection
|3i) Server commits transaction (this could result in DB updates if
|you don't
|have dirty flags on your entity beans)
|4) Client processes collection of ValueObjects and generates HTML table
|
|As you can see this method reduces the number of network calls dramatically
|and is more scaleable (because Stateless Session Beans are pooled).
|
|Check out some of the patterns at http://www.theserverside.com
|
|Hope that helps
|
|Jonathan
|
|-----Original Message-----
|From: Saul Farber [mailto:[EMAIL PROTECTED]]
|Sent: Thursday, 5 July 2001 1:01 p.m.
|To: [EMAIL PROTECTED]
|Subject: [JBoss-user] JBoss performance problems
|
|
|Hello gurus,
|
|I'm having some performance problems with JBoss right now. Could
|someone help me out a bit?
|
|Here's the scenario:
|
|Sun UltraSparc1-170Mhz:
|
| running: +Jboss2.2.1_Jetty3.1.RC4 bundle
| +PostgreSQL (ver 7.x)
|
|My app is pretty simple, just direct calls to entity EJB's from JSP's.
|However, when I try to load a page that essentially displays a whole
|table (all 30 rows) by using Home.findAll(), then running through the
|java.util.Enumeration object, it takes close to 30 seconds to load the
|page. This seems rather excessive. Could I have something
|misconfigured?
|
|If you need more info, please email me. I saw a similar post in the
|archives, but couldn't find a response to it.
|
|Thanks,
|
|Saul
|
|
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