Hi all,

I have problems (time-out) when processing a lot of data.

I've read somewhere that you should prevent using session variables because they are the reason the web application will be very slow. Is this true? Or does this depend on the amount of data (I am using the demo version)? Should I look for another way to filter my aggregates than use session variables? If so, could someone please explain to me, why?

Thank you


Hi Moonwatah,

Timeouts can occur in different places of the application, it would help to have more context to provide an answer with more help. 

Also, having many session variables should not originate timeouts, but depends on how you are using them.


Adding to Marco's answer, you can always take a look at the logs (Errors, General and Requests) to see if you can get more information.

Are your entities properly indexed? Which type of queries are you doing?


Hi moonwatah,

You should read this very informative post on how Sessions are handled in OutSystems and what are some of the considerations you should have in mind when developing applications that make use of them.

You can also check the best practices, you should probably follow it unless there's a very strong reason not to.

If you are having timeouts, I suggest you follow Armando's advice and go check on the logs what's causing them:

  • Check the Errors log for more information on what happened (you can get more information from the stack trace on the Error details page).
  • Check the General log for log entries from modules SLOW something, the platform considers anything that takes more than 200ms slow and will log it for you to analyse.
  • Check the Web/Mobile Requests logs to better understand which screens are problematic
  • Check the Integrations logs for web services calls (consumed and exposed) if you are using web services and want to check if the slowness comes from there.

Hope this helps!