Please Explain SRV.2.3.3.3 Thread Safety

Question

SRV.2.3.3.3 Thread Safety
Implementations of the request and response objects are not guaranteed
to be thread safe. This means that they should only be used within the
scope of the request handling thread. References to the request and
response objects must not be given to objects executing in other
threads as the resulting behavior may be nondeterministic.
My question is does a scenario arise often in practice? And if so,
could you let me know when.Basically what precautions should I take regarding this clause.

Answer 1

My question is does a scenario arise often in practice?No, because people are usually smart enough not to access request and response objects from several threads :-)
And if so, could you let me know when.If you access request and response objects from other threads.
Basically what precautions should I take regarding this clause.Don't access request and response objects from other threads. Don't store them in any static variable, or store them in some data structure where they can end up being accessed from random places.
As much as possible, access request and response only in the servlet. That is smart anyway: you don't want to pass them to your "business code" because that makes the business code less reusable and harder to test.
Usually this pretty much takes care of itself. There is rarely need to store the objects anywhere. One trap is declaring fields in servlets and storing something there. Never have fields in servlets, it is a bad idea because it is usually thread unsafe (except static final constants).