On Mon, May 19, 2014 at 8:11 AM, David kerber <dcker...@verizon.net> wrote: > > I've uploaded code examples and the JmxExample.war: >> https://wiki.apache.org/tomcat/Example%20Application% >> 20Exposing%20Internals%20Using%20JMX >> >> So, just deploy JmxExample.war to your Tomcat instance, open up JMX >> console >> through JVisualVM or JConsole, and find the MBean, e.g. >> JmxExampleApp:type=Counter >> >> You will see that the internal instance of MyCounter is exposed through >> JMX, and you will be able to set the name, initial count, reset the >> counter, etc... >> >> The trick was to use @WebListener that registers the MBean instance with >> your MBeanServer upon application deployment. Your MBean instance will >> wrap >> around any of your application internals you would with to expose. > >
> What kind of performance hit does this "wrapper" cause? A couple of my > app's instances take more than 4M transactions per day, up to several > hundred per second at peak times. So I can't afford much added work per > request. > > Thanks! > > Hey David, Well, that depends what do you do for every transaction (request). In the above example with @WebListener, the app's performance should not be affected significantly, all it does it registers a JMX MBean at app deployment, and exposes the attributes and operations (getters/setters + other public methods) to JMX clients invoke this MBean. Once you undeploy the app, it unregisters the MBean. Sure, performance will depend on how often you call JMX, and that might shave few OS cycles away from standard app operations (4M tx per day), if for example you want to make JMX calls every microsecond/second to plot some charts, etc... that might put a dent in your app performance. Few questions for you: - What kind of attributes/operations would you like to expose in your application, by using JMX? - What would you like to manage using JMX? It would be great to get some performance metrics and see how that affects your application! Keep us posted :) Cheers! n.
