We ended up having a lot of success reducing the footprint through tuning.  Bottom line: we reduced the memory footprint by 120MB, and the startup time from 53s to 24s

Here were the steps taken

The instructions for each step can be found : http://community.jboss.org/wiki/JBoss5xTuningSlimming

Notes on my environment and testing process:

• Windows XP, JDK 1.6.0_22,
• JBoss 5.1.0.GA.  Xmx=512M , Xmx=256 (this is why heap didn’t drop below 256)
• I used jvisualvm to watch the heap and “used” memory values
• For the “Used” memory, I took the maximum observed value while JBoss was starting.  If you understand that a time vs. memory usage graph follows a sawtooth pattern as objects are instantiated and garbage collected, then I took the value from the tip of the highest tooth.

-Java 7 is underwhelming, mostly because it will not have closures. It will however introduce enhancements to speed up Groovy, JRuby, and Scala

-If I read between the lines what features are in HTML and any of them are supported by Chrome, then I think that HTML5+Chrome could easily turn into a gaming platform!

-There is no question that Groovy is the “next big thing” for Java. Get on board.

-A java developer could easily add Hadoop to his resume (and dollars to his pocket), by learning Hadoop with Cascading. Hadoop-worthy scale data sets are available for free from amazon: http://aws.amazon.com/publicdatasets/

Grails is really cool. I wish there was a hosting platform available that was anything close to Heroku for Rails. I think it is unlikely that we will hear any good Startup stories with Grails for that reason.

The most surefire way to solve this problem is take the java bin path (ex: C:\program files\Java\jdk1.6.0_07\bin)  you want and prepend it to your System level PATH environment variable, as highlighted below.  This will ensure that you are executing the java.exe from the expected java installation every time.

Well here is my favorite JPA annotation cheatsheet.  Even though it says Oracle and Toplink it applies to any Spring/JPA/Hibernate technology stack:

http://www.oracle.com/technetwork/middleware/ias/toplink-jpa-annotations-096251.html

Oh yeah, and here’s my tip on using cascades: Never use CascadeType.ALL!  Use MERGE, PERSIST, and maybe REMOVE if you want to cascade your deletes.  CascadeType.ALL will result in poor performance and unintended consequences.

Environment Information:

JDK 1.5+
Eclipse 3.4.0
maven 2.0.10
m2eclipse 0.9.7 (maven plugin for eclipse)
Jetty 6.1.10
Spring
JPA,Hibernate

Maven Jetty Configuration:

In your maven project’s pomx.xml, in your <build> section, add the jetty plugin.  An example can be found at the Jetty website here:

http://docs.codehaus.org/display/JETTY/Maven+Jetty+Plugin#MavenJettyPlugin-WebappConfiguration

It is very important to keep <scanIntervalSeconds> set to zero.  This setting tells Jetty how often (in seconds) to scan the webapp for changes and if changes are found, it re-cycles the web container.  You don’t want to do this and setting it to zero will disable it.

Configuring Jetty to start within Eclipse:

Next, create an easy way to launch your jetty server.  I’m using Jetty through Maven and Eclipse.  Here is how I setup an Eclipse External Tool to launch my Jetty server:

To make sure it is listening for a debugger, make sure that a MAVEN_OPTS environment variable is set with the following options:

-Xdebug -Xnoagent -Djava.compiler=NONE -Xrunjdwp:transport=dt_socket,address=4000,server=y,suspend=n

The address parameter is what port the jetty server will be listening on for the remote debugger.

Click ‘Run’ and your jetty server should start running in Eclipse’s console window.  It should look something like this (depending on your log4j config):

Listening for transport dt_socket at address: 4000

[INFO] Scanning for projects...
[INFO] Searching repository for plugin with prefix: 'jetty'.
[INFO] ------------------------------------------------------------------------
[INFO] Building myProject
[INFO]    task-segment: [jetty:run]
[INFO] ------------------------------------------------------------------------
[INFO] Preparing jetty:run
2010-05-27 15:39:25.733::INFO:  Started SelectChannelConnector@0.0.0.0:8080
[INFO] Started Jetty Server

Attaching the Debugger:

Next, setup a debugger.  In Eclipse open ‘Debug Configurations’, and create a new ‘Remote Java Debugger’.   Select your eclipse project, set the host to localhost, and set the port to 4000, or whatever you defined earlier.

Press the Debug Button and the remote debugger should attach to your jetty server.

Finally, make sure Build Automatically is enabled in eclipse (Project->Build Automatically).

At this point your environment is enabled for debugging code on your Jetty server through Eclipse.  Breakpoints, watch variables, you name it.

Hot deploy is also enabled.  If you modify some java code, the automatic builder should compile the .java file to a .class file.  The remote debugger will see it and use it, all without restarting your jetty server or its web container.  This will not work for things like adding static variables, new domain classes, or new injectable service methods that require the application to acknowledge them on startup.