What are the primary reasons for Session object expiration?

There are several main reasons for the expiration of the session object:

1. Timeout: Servers can control the validity period of a session by setting a timeout for the session. Once this time has passed, the session will automatically become invalid.
2. Manual invalidation: The server-side has the ability to manually invalidate a session object, such as when a user logs out or logs off, by setting the session as invalid.
3. Conversation lost: when a user opens multiple tabs or windows in the same browser, and logs out or closes the session in one of them, the session in the other tabs or windows will also be terminated as they share the same session.
4. Server reboot: When the server restarts, all session objects will be cleared, causing the sessions to become invalid.
5. Load balancing in a distributed environment: When using a load balancing strategy in a distributed environment, requests will be distributed to different servers, each with its own session data. This may result in session object invalidation on different servers.