Vaadin UI detaches after some time


I’m using Vaadin 7.1.2 and rely heavily on its push notification support. Everything works well for some time after the application starts, but then after about 30-40 minutes suddenly it stops pushing updates from the server and instead logs com.vaadin.ui.UIDetachedException on every update event. Restart helps but for very long.

All configuration parameters are default except I had to add the
command options for push to work.

I deploy to Tomcat 7.0.36 and everything is set to default in its configuration as well.

To update UI I simply call

ui.access(new Runnable{...});

on the UI instance which I pass down to every component from the UI.init() method.

Am I missing something?