preface

When it is time to recruit, I have sifted several new ones these days. I feel that the current recruitment mechanism is too disgusting and needs to be improved. By the way, I will prepare the questions that may be raised in the interview and share them here.

Specific questions

1. Hashcode equality Are two classes necessarily equal? equals? On the contrary?
2. Do you know bytecode? What are the bytecodes?
3. Why don’t you talk about class loading? What class loaders do they have, and what files do they load?
4. What JVM optimizations have you done? Using what method? To what effect??
5. Do you know osGi _ how it is implemented?
6. Class. ForName(” java.ian.string “) and String.class.getClassLoadero.ioadClass (” java.ian.string “)
7. What are the mechanisms of Spring? How does AOP bottom implement ah? The IOC?
8. Does CGLIB know? How does it differ from JDK dynamic proxies? Write a JDK dynamic proxy?
9. What serialization protocols does Dubbo support? hessian? What about hessian’s data structure? Does PB know? Why PB efficiency is the highest ah?
10. Why is the system split? Can we split it without dubbo? What’s the difference between dubbo and th Rif t?
11. HTTP workflow; Http1.0,http1.1, http2.0
12. TCP three times handshake, four layers of break up workflow draw a flow chart why not four times five times or two ah
13. So let’s draw the HTTPS workflow and how do we implement it and how do we prevent packet capture
14. Relatively simple, I have a file, there are 4.5 billion Arabic digits, how to go to find the largest number ah?
15. What are the principles for using mysql indexes? What data structures are indexed? What is the difference between B+tree and B tree?
16. Binary trees and red black trees. I
17. What storage engines does mysql have? What’s the difference? 7 Be detailed!!
18. How to design database level of high concurrency system?? What are the types of database locks? How to do that
19. What are database transactions?
20. How to design the dynamic expansion and reduction of the database and table scheme??
21. How to limit the current in the project how to do, say concrete realization
22. What sub-database sub-table middleware has been used? What are the advantages and disadvantages?
23. I now have a system that is not divided into database and table, and then the system needs to be divided into database and table, how to design, so that the system that is not divided into database and table dynamically switches to the system that is divided into database and table?
24. What is the working process of es query? What is the difference between ES and Mongdb?
25. How do you degrade how do you split systems, how do you split databases
26. How to fuse the fuse frame has what concrete realization principle to know
27. How to Use cache What are the consequences of improper use of cache
28. Distributed transactions? How did you solve it? TCC? That if appear network reason, network connect impassability how to do??
29. What are the algorithms for distributed addressing? Do you know consistency hash?
30. What’s the difference between Redis and memcheched? Why is single-threaded Redis more efficient than multi-threaded memched?
31. Write Java implementation code 7 by hand? If userld retrieves shard, what if I want to retrieve data over a continuous period of time?
32. What data types does Red is have? In what scenarios are they used?
33. How is master-slave replication implemented for REids? How is the Redis cluster model implemented? How is redis key addressed?
34. How to design distributed locks using Reds? Is zK ok? How do you do that? Which one is more efficient?
35. Do you know about redis persistence? What are the disadvantages? What is the underlying implementation?
36. What are the Redis expiration policies? LRU? Write the Java version of the code?
37. What is the implementation of Dubbo? Can I continue to communicate when the registry is down?
38. Do you know the zK principle? What can ZK do? P8xos algorithm know? Talk about the principle and implementation?
39. Do you know netty? What is N10,B10,A10? What’s the difference?
40. What are the dubbo replication balancing and high availability policies? Dynamic proxy strategy?
41. Why message queues what are the advantages and disadvantages of message queues
42. How do you ensure that message queues are highly available how do you ensure that messages are not re-consumed
43. How do you ensure that message queues are highly available how do you ensure that messages are not re-consumed
44. If you were to write a message queue, how would you architecture it
45. How is the working process of ES implemented? How is it distributed
46. Es in the case of a large amount of data (billions of levels) how to improve query efficiency ah
47. Talk about LAYER 4 of Tcp ı P
48. How to design a high concurrency high availability system
49. What about collections framework?
50. What are the differences between the underlying implementation of HashMap Hastable? Hashtable and concu rrenthashtableDE?
51. What is the difference between hashMap and t reemap? What are the low-level data structures?
52. Have thread pools been used? What are the parameters? How is this implemented at the bottom?
53. What’s the difference between sychnized and Lock?
54. What is ThreadLoca? How is it implemented at the bottom? Why don’t you write an example?
55. How does Volitile work?
56. Does CAS know? How is it done?
57. Please write a singleton pattern in at least four different ways?
58. Introduce the JVM memory model? What garbage collector have you used? Just say it all
59. How to handle full GC frequently sent online? What can I do if the CPU usage is too high?

About the answer

There are references for each of the above questions on the Internet, but I won’t link to them due to space limitation, but if you are interested, you can send me a private message.

conclusion

I think the interview is the same. Before you are ready to ask others, you should first think about the questions you want to ask. In this process, your level has been significantly improved. If you want to evaluate the technical level of the interviewer well, you must have a good foundation so as not to be fooled. At the same time, you must keep a good attitude so as to evaluate others objectively.