Memory and performance

I m quite a newbie to vaadin, and like many people i do have questions about scaling/memory capabilities.
I was wondering if there was some metrics available to
roughly a high mark of the memory used in http session related to the number/type of ui components used.
I looked in the forum but did not find a detailed response (may be my fault).
We are currently have a business production application (Flash / Tomcat) that handles 200 to 500 concurrent users with each of them 5 to 10 forms opened simultaneously; a form typically contains 20 to 50 widgets (comboboxes, date picker, number fields) plus a couple of grids (not less than 3) with 10 to 100 items each. It currently runs smoothly with 8Gb quad core processors… and are investigating alternative technologies.
By advance thank you for any light on that subject.


to get accurate results, you should try the VisualVM tool by Oracle (available at
). Just point it to the JVM instance running your application and take a heap dump. you might want to click on Perform GC before the heap dump to get all the unused instances out of the memory. After that look for HttpSession in the Classes tab and double-click it to show all instances and their “retained size”. This is the amount of memory used by the Vaadin application.

Of course before taking the heap dump you need to make sure there’s actually a reasonable amount of sessions running on the server - so run a load test or whatever you need to in order to generate the load on the application.