This article explains how to enable log4j logging and how to change configuration to generate different levels of logs in a web application. It also tells how to enable logging for different frameworks like Struts, Spring, Hibernate etc.

Java 5 and later provides tools with JDK to generate thread dump. jconsole is one option which connects to the running JVM and provides graphical interface to access JVM data. Another option is using jstack to generate stacktrace of certain instance. I came across a scenario, where, there was a conditional requirement to generate thread dump