Lately I’ve had a problem with one of the applications made with Vaadin 7 with style valo. What happens is that when many people go into the application it is loading and not resumed until it does not re-enter, but other applications are running properly.
For the application server I use Apache Tomcat / 7.0.42 and when I enter the manager to see what happens shows me the following:
(S 4314689 ms 0 KB 0 KB 190.250.160.81 plataformaincontacto.com GET /xxxxxces/VAADIN/themes/festival/styles.css HTTP/1.1)
Apparently it’s a problem with the style. If I can help them appreciate it, since the application touches me be restarting every so often on the same day.
Are you using on-the-fly compilation of the theme? Otherwise, this would look like a general server issue to me rather than a Vaadin issue.
For production deployments, I’d strongly recommend precompiling your theme from SCSS to CSS using the Vaadin Eclipse plug-in or Vaadin Maven plug-in (goal vaadin:compile-theme). You should have the file styles.css in your WAR after this, and serving it should typically only take a small fraction of a second and the time other users are blocked should be at most a few milliseconds. Note that once the theme has been precompiled, on-the-fly compilation is not used so you should probably remove the file styles.css from your development environment.
Latest (and future) Vaadin versions should be better at caching on-the-fly theme compilation results, so you should be less likely to run into this even if you forget to precompile the theme.
In any case, the extreme loading times you are seeing should not happen, but analyzing the issue might require more information about what exactly was happening.
If it happens even with the precompiled theme in the WAR, I suspect there is some problem with your server - perhaps it is getting close to an out of memory situation or there is some configuration issue. Also, in case you are using server push and websockets, there might be some bugs in the Tomcat implementation of websockets - I don’t remember which version fixed those, but upgrading to the latest Tomcat 7.0.x might help in that case.
Try checking the memory usage of the server (though the problem could also be e.g. just the permgen getting full), and perhaps use jstack to get a list of the active threads. Note that it is normal that there is a large number of Atmosphere (push) threads if your application uses server push.
Check the loading times of some static resource, e.g. VAADIN/themes/valo/favicon.ico .
Does a server restart help? If not, more information is probably needed.
