Number of threads


Is vaadin bounded by any number of threads it can run per instance?

Vaadin is single-threaded. There is no limit for the parallel instances in Vaadin itself, although your Servlet-/Portlet-container will have some configuration-variables to set one.

EDIT: Of course it is possible to spawn background-threads inside a Vaadin-application, but you should note that the JEE-spec actually forbids this. Most Applicationservers provide some kind of ThreadFactory or ExecutorService which can spawn Threads that are managed by the server (which is ok for the spec). If you are manipulating the UI from a background-thread you need to synchronize either on Application (Vaadin 6) or VaadinSession#getLockInstance() (Vaadin 7).


Is the synchronization you mentioned still needed if I use ICEPush or DontPush add on?

Yes it is.