Ali was hanged and beaten during an interview with Shuo Er, unwilling! Rehearsal of the underlying technology, won Ali P6+ offer

Things are like this

This article is a reader’s experience sharing interview with Ali. Although it was said that it was cold after the second interview, the interview experience was very rewarding and helpful for him.

Let’s take a look at what questions were asked in this interview. The following questions are both high-frequency interview questions and very representative interview questions.

Alibaba side

• I won’t talk about self-introduction, I must ask at the beginning
• Talk about StringBuilder and StringBuffer
• Spring bean loading and instantiation process
• Have you seen the Spring AOP source code?
• Java memory model talk about
• If you are given a map with many objects in it, where is the map stored?
• Do you know the GC algorithm?
• Talk about the CMS garbage collector
• The difference between B+ tree and B tree?
• Let's talk about the bottom of haspmap
• The underlying implementation of ConcurrentHashMap?
• Is CAS implemented in hardware or in software?
• Is volatile a lock?
• What do you think is the difference between Taobao and Jingdong?

Project related:

• Tell me about the items on your resume? What do you mainly do?
• What do you think is the biggest challenge for you in the project? What's the problem? How to solve it? What have you learned from it?
• Can you draw the structure diagram of the project?
• What areas do you think can be improved?
• What if I have many fields that need to be indexed?
• Mysql storage engine, which one do you use?

Code side:

• Design a multi-threaded printing program, the i-th thread only prints the number i-1, for example, the first thread prints the number 0, the second thread only prints the number 1, and so on. Any given number sequence, such as 3382019835830, can be printed out using this program.
• Quickly find two numbers in an array and make the sum of these two numbers equal to a given value. For simplicity, we assume that there must be at least one set of solutions that meet the requirements in this array.

Two sides of Alibaba

• Talked about the project again
• You said you used UDP in your project, why don't you use TCP
• Then you elaborate on the difference between TCP and UDP
• What is the database used (MySQL)
• What is your data volume (several millions)
• What query optimization (index) did you do for these millions of items?
• How to build the index
• Why use time and id for indexing?
• The isolation level of the database
• Do you know what is master-slave replication?
• Tell me about the rules for indexing
• JAVA class loading mechanism (load verification is ready to parse and initialize, and also talk about the parent delegation model)
• Talk about all the parameters of the thread pool
• The underlying implementation of ConcurrentHashMap
• Have you used RPC?
• What about the message queue?

Summary: I asked some basic things before, and then I kept asking in depth, basically asking questions about the project, because what I did before was a small project in itself, and there were no bright spots. I just finished it. I went back and waited for the notice, and the result must have been cold.

Learn lessons and break through the underlying technology

In fact, every interview, regardless of success or failure, is a good learning opportunity, so we must take every interview seriously, sum up the experience from the interview, literacy during the interview, and then go home to check the missing.

Review preparation, direct to Alibaba

Understand learning related knowledge

During this period of time, I kept looking for materials to learn, and through many channels and friends, I asked for a Java Interview Book (284) written by Meituan architects. I finished a Java Interview Book by Meituan architects. I also found the Java back-end and the interview scenes and interview questions of some major companies, constantly brushing the questions to improve my vision

How to get information: forward and comment on this article, then follow the editor, add assistant VX: MXW5308 to take away all the information~

Java core interview book review knowledge

This Java core knowledge parses each point of knowledge very deeply, which should be very helpful to everyone. It gathers most of the Java knowledge and analyzes it in depth (it is highly recommended for everyone to take a look)

1. JVM
2. JAVA collection
3. JAVA multithreaded concurrency
4. JAVA basics
5. Spring principle
6. Microservice
7. Hetty giving PC
8. The internet
9. Log
10. Zookeeper
11. Kafks
12. Rabbi tMQ
13. Hbase
14. MongoDB
15. Cassandra
16. Design Patterns
17. Load balancing
18. database
19. Consensus algorithm
20. JAVA algorithm
21. data structure
22. Encryption Algorithm
23. Distributed cache
24. Hadoop
25. Spark
26. Storm
27. TOMORROW
28. Machine learning
29. cloud computing

 

The interview scene from Dachang I asked for (in order to learn to improve, it can be faceless and skinless, hahahaha)

I also found a lot of questions for the face-to-face scenes of these big companies, which improved myself greatly (I also asked for an interview answer)

 

Part of Meituan

 

Good future interview scene

 

Share some of my personal learning documents, friends in need can choose to obtain them:

1. Arrangement of interview documents

Since it is an interview, it is indispensable to brush the questions. In fact, after I go home during the Spring Festival, I can’t go anywhere. I have brushed a lot of interview questions myself, so I can know it well during the interview process, and I will basically know it. What knowledge points will be asked during the interview, and what are the high-frequency questions, so brushing the questions is a very important point in the pre-interview preparation process.

Organized according to my own interview experience and continuously collected (collector's edition)

 

Related e-books, underlying source code

 

Alibaba must learn knowledge points

 

At last

Many people lament that "learning is useless". In fact, the reason for the useless theory is that what you want does not match what you have learned, which means that you have not learned enough. Whether it is studying or working, there should be initiative, so if you have the dream of a big factory, you must work hard to realize it yourself.

The above learning materials are all free of charge. Finally, I wish you all good health and successfully get your favorite offer!

How to get information: forward and comment on this article, and then follow the editor, add assistant VX: MXW5308 to take away all the information~