Inconsistent Session Retrieval in Legacy Spring MVC App: Redis vs. Tomcat HttpSession

I'm encountering an inconsistency in session retrieval within my legacy Spring MVC 5 application deployed on Tomcat 9. Specifically, I'm observing different behaviors when retrieving sessions using RequestContextHolder based on whether the session is managed by Redis or Tomcat's HttpSession.

Here's a breakdown of the issue:

Redis Session Management:

• Implemented Spring Session with Redis for session management using @EnableRedisHttpSession.
• Configured a RedisSessionConfig class to define the Redis connection factory using Lettuce.
• Verified successful connection to Redis and configured Spring MVC to use Redis for session management.

Tomcat HttpSession:

Default session management provided by Tomcat's HttpSession.

Observations:

• When obtaining the session object using HttpServletRequest.getSession(), it consistently returns the Redis-backed session object, indicating that Redis-based session management is being used.
• However, when attempting to retrieve the session using RequestContextHolder, the behavior is inconsistent:RequestContextHolder.getRequestAttributes().getRequest().getSession() consistently returns the Tomcat HttpSession object.There is no observed instance of ServletRequestAttributes containing the Redis session object when using RequestContextHolder.

Desired Outcome:

• Ensure consistent session retrieval behavior across the application, regardless of whether the session is managed by Redis or Tomcat.
• Understand the reasons behind the inconsistency observed when using RequestContextHolder to obtain sessions.
• Determine if there are specific configurations or best practices to follow to ensure reliable session management with Redis in a legacy Spring MVC application deployed on Tomcat 9.

Has anyone encountered similar issues with session retrieval in legacy Spring MVC applications using Redis and Tomcat's default HttpSession? How can I ensure consistent session management and retrieval behavior across the application?

Any insights, suggestions, or guidance would be greatly appreciated. Thank you!