solution
1. Nignx uses ip_hash; load strategy.
Advantages: simple configuration,
Disadvantages: A Tomcat hangs up, and the Tomcat's Session is lost
2. Tomcat broadcast
Communication with multiple Tomcats, duplicating sessions, takes up a lot of system resources, occupies io streams, and is not recommended
3. Third-party centralized and unified management, such as redis, mongobd, mysql, etc.