Jenkins kills Tomcat or other Java process after job ends

Recently, I was adding new application deployment to Tomcat server that was started by Jenkins. Process was starting nicely, but was stopping at the end of the job. The only clue was log record:

Service exit with a return value of 143

This issue can be easily solved by adding -Xrs to JAVA_OPTS. Option description can be found at http://docs.oracle.com/javase/6/docs/technotes/tools/windows/java.html.

ActiveMQ pool logging

If you are using org.apache.activemq.pool.PooledConnectionFactory for ActiveMQ connection pooling, it is maybe frustrating to detect server connection problems as it does not log anything at INFO level. DEBUG level contains reconnection records, but also a lot of unnecessary, boring stuff, not needed for production. Fortunately, there is logger that can be used for connections monitoring, which is not nicest, but working solution, and definitely it is better than nothing:

    debug 'org.apache.activemq.util.ThreadPoolUtils'

Javamelody SQL monitoring with Grails plugin

Javamelody is amazing tool for live monitoring. It has great Grails plugin which makes it very easy to use. Only issue I had with it is SQL monitoring configuration.
According to documentation there are several ways to configure data sources:

1. magic - you don't have to do anything, it just works
2. javamelody.datasources property in GrailsMelodyConfig.groovy - you just specify datasources
3. replacing JDBC driver with Javamelody proxy
4. specifying java option - javamelody.datasources

Unfortunately, all internal configuration options (1, 2, 3) didn't worked. As I investigated (quickly) it looks like there is no dataSource bean available for BeanPostProcessor and it tries to proxy after all connections were already picked by application.
So only specifying java command line option worked for me. Otherwise - great tool. It is also possible to specify multiple data sources with command line like:

-Djavamelody.datasources=java:comp/env/ds1,java:comp/env/ds2

Logging in Struts 2

Struts 2 provides a lot of logging information. To enable it in debug mode, just create log4j.properties file in classpath and add the following content:

log4j.rootLogger=DEBUG, A1
log4j.appender.A1=org.apache.log4j.ConsoleAppender
log4j.appender.A1.layout=org.apache.log4j.PatternLayout
log4j.appender.A1.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n