Recently, a lot of friends went to the current mainstream large Internet companies for interviews (Alibaba, JD.com, Meituan, Didi), and they will send me some interview questions after the interview. Some friends passed the test easily and got the offer, but some came to ask me for the answer.
In fact, I really didn't plan to write this article, mainly because my memory is not very good. Unlike some people with strong memory, after the interview, I can almost write down the conversation between myself and the interviewer. After my initial interview, in addition to remembering some of the knowledge points I talked about, I basically forgot the specific content, so writing this article is actually very difficult.
However, there are too many people who have asked me recently. In order to avoid repeated answers and save myself some energy, I simply reply here. To be honest, I can only vaguely think of the keywords of concurrency, JVM, distributed, and TCP/IP protocol, and I hardly remember the specific problems. And even if I remember it and tell you, you know it by heart, but I think it's still very unlikely that you'll be asked the exact same question in an interview. Even if you are lucky enough to be asked, and you memorize it, it may not be able to play a positive role in your interview, because if the interviewer asks more questions, you may be exposed. It's better to just say it's not better. Here are some interview questions for large Internet companies. 
Let’s take a look at the interview materials I recorded:
1. Interview with Alibaba
The first one: What did Ali ask in the interview? : (55 minutes)
1. What data structures are used in Java in development?
2 Talk about your understanding of HashMap, the basic implementation of the underlying principle, and how does HashMap solve the collision problem?
Are these data structures thread safe? If you answer that HashMap is thread-safe, then ask if you have a thread-safe map, and then ask the conurren package.
3. Are you familiar with JVM? Briefly talk about the class loading process, what operations are performed in it? I asked about GC and memory management, and is there any related configuration in tomect?
4. Then I asked the http protocol, the basic difference between get and post, then tcp/ip protocol, three-way handshake, and window sliding mechanism.
5. Which databases were used in the development? Answer mysql, what are the storage engines? Then asked me about the usage scenarios of pessimistic locking and optimistic locking, and the principles of distributed cluster implementation.
6. Then he asked me how springmvc and mybatis work. Have you seen the underlying source code?
2. JD Finance Interview
1. Dubbo timeout retry; Dubbo timeout setting
2. How to ensure the order of execution of requests
3. Distributed things and distributed locks (do not show negative numbers for deductions)
4. Distributed session settings
5. Perform a certain operation, the first 50 times are successful, the 51st time fails a roll back all b the first 50 submissions throw an exception at the 51st time, how to set Spring (propagation) in ab scenarios respectively
6. What are the uses of Zookeeper
7. JVM memory model
8. The database is split vertically and horizontally
9. How does MyBatis paginate; how to set up the cache; MySQL paging
10. Are you familiar with IO? The difference with NIO, the difference between blocking and non-blocking
11. Distributed session consistency
12. The idempotent design of the distributed interface "cannot be deducted repeatedly"
3. Meituan Interview
1. What is the most familiar project you have done recently? Draw the project technical architecture diagram
2. What is the ratio of the old generation to the young generation of the JVM?
3. The specific scene of YGC and FGC
4. What are the meanings of jstack, jmap, and jutil? How to troubleshoot JVM related issues online?
5. What are the specific meanings of the five parameters of the method of constructing the class of the thread pool?
6. What should I do if a thread pool on a single machine is processing services suddenly? (How to process and block requests in the queue)?
7. What are the problems with using unbounded blocking queues?
8. How does the interface handle repeated requests?
9. What is the specific treatment plan?
10. How to ensure the atomicity of shared variable modification?
11. Design an interface implementation class for external services, and implement load balancing and sequential polling mechanisms on the three hosts 1, 2, and 3 (corresponding to different IPs) (considering concurrency)
4. Didi Interview
1. Self-introduction, technical characteristics
2. What are your interests and advantages
3. The relationship between jvm, jre and jdk?
4. The underlying principle of Dubbo, what is Zookeeper
5. The mechanism of cincurrentMap; TreeMap; Volatil keyword
6. Quick sort; Breadth-first search (queue implementation)
7. Understanding of cache avalanche and penetration?
8. Can the key of HashMap be repeated?
9. What is the difference between synchronized and lock?
10. What issues will you consider when developing a large website?
Summary
The above is to collect and share the interview questions of large-scale Internet famous enterprises, and share them with you. I hope you can understand what are the interview questions of large-scale Internet famous enterprises. If you feel that you have gained something, you can click, follow, favorite, and forward a wave, thank you for your support!
Java programmers came back from interviews in Ali, JD.com, and Meituan. Do you know these interview questions? (with answer)