Usnig session as instance variable

Question

Many methods of my Servlet use HTTPSession. It is thread-safety to declare HTTPSession variable as instance variable?

Answer 1

By defaut Servlets are not thread safe . And moreover, a servlets instance will invoked for many clients. It is absolutely wrong to have session as instance variable.

Reference:

Is a Servlet thread-safe

Write thread safe servlets

Answer 2

No, it is not safe. a servlet is created when the application starts. The Servlet has only one instance (which means multiple requests/clients use the same servlet), which is why you should avoid having any instance variables.