Are the singleton objects created from Spring beans in the same way as there is SingleThreadModel where only thread can access at once? Since in Spring only 1 object of are created from the beans, if multiple threads try to access the application then wont the case be like SingleThreadModelservlets?
Basically, if you have a stateless object. Then a single instance can run with as many threads as your Operating System allows. Each thread can run the same method in the same instance all simultaneously without any problems
Problems only occur when your object is holding state. Meaning it has instance variables that each thread might change to different values. but 99.99% of your beans you configure in Spring will be stateless classes like your Service and Repository classes. If you find you ahve object holding state that you want as Spring Beans, look at your design and you will see a code smell there.