This article is about a real problem I faced where the timezone on a Java application server (in my case it was JBoss) changed unexpectedly during the run time of the server. It was hard to find any pattern or the reason for the change, as it was triggered by a HTTP request. To debug this scenario, I used the Byteman tool and injected the script into the JVM. This helped me to identify the root cause of the issue and come up with a few Do’s and Don’ts for a shared JVM (like on Java application servers).
Any application server is considered a shared JVM. There are multiple applications deployed on the JVM and they share the same resources. In such a scenario, there are some precautions which need to be taken care of. One of them is dealing with the JVM’s timezone.
Byteman is a tool that makes it easy to trace, monitor, and test the behavior of Java applications and the JDK runtime code. It injects Java code into your application APIs or into Java runtime methods without the need for you to recompile, repackage, or even redeploy your application. Injection can be performed at startup or in running code.
Continue reading “Using Byteman to Find Out Why the TimeZone Changed on a Java App Server”
In my previous article, Enabling Byteman Script with Red Hat JBoss Fuse and AMQ – Part 1, we found a basic use-case for Byteman scripts with Red Hat JBoss Fuse or Red Hat JBoss AMQ. However, the log file was generated separately and only limited operations were possible. In this article I will show you how to use a Java helper class. By using Java, we get advanced operations to view or modify the content. Also, using java.util.logging allows us to log the statements to fuse.log, avoiding the creation of any other log file.
Continue reading “Enabling Byteman Script with Red Hat JBoss Fuse and AMQ – Part 2”
In a production or customer environment it is not always possible to identify issues by looking at logs, nor is it always possible to setup remote debugging using an integrated development environment (IDE) and remote debug port. Often the issues are specific to the environment and can’t be reproduced. Having byteman scripts can help in these situations to identify issues without actual code changes. Whenever certain java class or logic is invoked, byteman scripts will also be invoked as per defined class and method in the byteman script.
Continue reading “Enabling Byteman Script with Red Hat JBoss Fuse and AMQ – Part1”