Spring Singleton & Concurrency

A good post with Java champs about Singleton, concurrency, instance variables & static:

http://richardchesterwood.blogspot.cl/2011/03/using-sessions-in-spring-mvc-including.html

https://stackoverflow.com/questions/37595841/spring-scope-usage-for-instance-variables

@Scope(scopeName = BeanDefinition.SCOPE_PROTOTYPE, proxyMode = ScopedProxyMode.TARGET_CLASS)

https://coderanch.com/t/661307/framework/singleton-concurrent-access

https://docs.spring.io/spring/docs/3.0.0.M3/reference/html/ch04s04.html