Paytm Java Back-end Developer interview questions

1.API Gateway 2. Besides routing requests, what additional things can we implement inside an API Gateway? 3. You just implement the monolithic application to microservice architecture in your application, What pattern you follow on that? 4. What you have done for making your monolithic into microservice what steps taken etc. 5. What is Beck Pressure? 6. What is seriallization? 7. Extrserialization or something what it is? 8. Synchronisation and locking diff? 9. What Data structure is used in HashTable and why? 10. Priority queue. So, which data structure is used in priority queue? 11. TreeSet. So, which data structure is used? Is it thread safe? 12. LinkedHashSet. So, which data structure is used ? Is it thread safe? 13. In LinkedHashSet can we insert null? 14. What order does TreeMap stored and how it maintain that order what it used internally to do that? 15. How Caching works and what it is? 16. Cache Hit vs Cache Miss? 17. Common cache placement strategy like how you will place the cache between the user is accessing and your application is providing the data. 18. Type of Caching? 19. Cache Algorithm? 20. Find Subsets of given array?