Ali interviewer's surprise interview, was asked to autistic on the spot! ! !

Preface

       I heard that Ali likes to conduct surprise interviews. At around 9 pm, I suddenly received a call. Said it was Ali's, and then started the phone interview, really caught off guard. Share a wave of experience!

Phone face

1. Questions related to the spike project:

• How to optimize Redis for a single product with 10w+ inventory?
• How to improve efficiency without oversold
• Whether the program itself is multithreaded

1. Do not use any optimization, directly access the database, how to optimize (hint redo, undo log overhead)
2. Principle of Distributed Session
3. The underlying structure of HashSet
4. JVM class loader, parent delegation model
5. springMVC, answered the process of DispatherServlet
6. Why is single thread fast
7. How to achieve multithreading
8. Thread pool type, rejection strategy
9. MySQL index, why use B+ tree
10. Evaluation questions:

     At the Double Eleven party, Xiao Ming won a chance to waive orders from Tmall Supermarket and enjoy free orders within the maximum volume V and maximum weight M of a package. Assuming product i, volume Vi, weight Mi, inventory Si, and price Pi. At present, Tmall’s products are divided into four categories: fresh aquatic products (1), food and beverages (2), beauty and personal care (3), and home life (4). Fresh aquatic products are not packaged with beauty and personal care. Please help Xiao Ming add goods to the shopping cart to maximize the total value

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one side

1. What do you think about the process of exporting data? Is your optimized step in the process of reading data or writing data? In the process of writing excel, the data stream is not closed, is it always in memory?
2. Can you open the data stream to write a part, then close it, and then open it to write a part
3. If you did a big data download and the memory was insufficient, what would you do? 
4. Let's talk about the database, what is the storage structure of the database?
5. Why use B+ tree?
6. What are the characteristics of data transactions?
7. Are you clear about cross-link transactions?
8. What are the isolation levels of the database
9. The difference between java process and thread, give a practical example
10. How do processes communicate, how do threads communicate
11. What is the role of volatile and how is it realized? Where have you used it?
12. What singleton patterns are you familiar with?
13. Spring's AOP is based on dynamic proxy. How is dynamic proxy implemented? Which ways to use
14. What is the principle of Cglib implementation?
15. What is the principle of java class loader-parental delegation
16. Why does the parent delegation need to be from top to bottom?
17. What if you want to implement a java.lang.string?
18. Will the loader be customized?
19. What design pattern does springIoc use? What is springIoc used for in spring?
20. How to implement redis distributed lock?
21. Have you learned Kafka, right, Kafka has an asynchronous model and a synchronous model?
22. What are the advantages of the asynchronous model over the synchronous model?
23. The difference between countdownLatch and Thread.join
24. What is data skew?

to sum up

At this point, Ali was over with only one side, after all, he was still not fully prepared. So in the end, I will sort out all the interview questions and answers of all major companies in 2020!

Click here to receive it for free, the secret code: CSDN , there are more interview topics and videos from major companies!

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