Top Most JAMon

Years ago I discovered a little gem in the world of a free and open source software: JAMon.

Still in use today, JAMon's mind-numbingly simple API provides a wealth of value for minimal effort. JAMon has now spawned competing products, each with its unique pros and cons.

JAMon is called a lightweight monitor. This may disappoint those who prefer large, feature-filled enterprise level commercial products, but the reality is JAMon delivers most of the data you need with minimal impact on performance. I would never consider developing a Java application without JAMon or some other monitoring solution. (JAMon is available for other languages as well.)

Best of all, you can have JAMon up and running in a few hours (or less)!

JAMon excels at timing code execution. Without any code changes you can configure JAMon to monitor SQL, method calls (via Spring AOP), as well as application entry and exit points.

In addition to execution time, JAMon allows you to monitor ANY data that can be expressed numerically. Common usage includes the number of users by hour of the day (to find usage peaks), simultaneous users, memory, heap size, session size, # of active sessions, and so on.

JAMon accumulates statistics rather than details which allows it to minimize its memory footprint. As it turns out, that is an excellent comprimise. JAMon keeps track of the number of invocations, min, max, average and standard deviation, as well as the min, max and average number of simultaneous executions, which is great for bottleneck analysis.

Although criticized for its inability to save statistics to a persistent store, you can do so with a little work if needed. You can persist statistics to a database, log file, expose them via JMX, etc.

You can configure JAMon start and stop monitoring dynamically. JAMon is typically measured at less than one percent overhead while turned on, and much less when turned off.

So if you have no monitoring (or your monitoring solution cannot be run in production), try JAMon or one of it's competitors. Documentation is a bit on the light side but there are plenty of examples on the Web.

And if you are a Grails developer, look for my posts about how to create a simple plugin to enable JAMon in your Grails applications.