Where to synchronize struts 1.1

[Picus Ameradeus]

Hello,

I need to thread safe a very basic struts app. It get user info and inserts it into a db, but there are sessions involved.

The app uses two model classes, users and orders, each with getters and setters that handle instance variables through the action classes..

My question is this,

Do I thread safe the getter and setters on the model classes or do I synchronize the execute methods on the Action classes?

I assume both are fine but are there performance issues?