The material of this article comes from the self-report of a programmer in Alibaba factory

Preface

A summary of the experience from Ali on all sides

I think there is one who can find a big factory offer Ideas , It's normal , This is not our talk after dinner, but the pursuit of every technical person . Like Ali 、 tencent 、 Meituan 、 Bytes to beat 、 The technical atmosphere and technical standard degree of Jingdong and so on are obviously better than some entrepreneurial companies / A small company , If I could exercise in such a company for several years , I believe that the improvement of my ability is still very big . Both school recruitment and social recruitment can not avoid all kinds of interviews 、 written examination , How to prepare these things is particularly important . There are rules to follow in both written and interview .

Because the interview in large factories is usually done by a professional team , Do you master a certain knowledge point or simply recite it , As soon as the interviewer asks, you can see that （PS： It's really time for an interview, especially when you don't have enough time to prepare for the interview , You can pick out some of the most frequently asked questions in an interview , Pay attention to understanding , Never learn by rote ）. Don't put too much hope on all kinds of books , Try to improve your comprehensive ability .

“ 80% Of offer Master in 20% 's hands ” This is not unreasonable . Strength is a big part of the factors that determine your success in an interview , But if you don't have the mentality or the luck , Still can't get satisfied offer. Let's not talk about luck , Take mentality , Don't be discouraged by the failure of the interview or doubt your ability , Summarize the reasons for the failure after the interview , Then you will find that you will become more and more powerful .

Ali often asked what skills he had

data structure , Multithreading ,jvm,Spring, Optimize , Message frame , Distributed , cache And the framework you've used and the foundation of the first round is important , After passing the meeting, the possibility of admission is relatively high ！

one side （ Mainly jvm, Concurrent , lock , Data structure, etc ）

1. Self introduction. （ Talk about your skills and skills ）
2. say something treemap and HashMap The difference between ？HashMap and ConcurrentHashMap The difference between ？
3. HashMap How does the underlying layer achieve (JDK1.8 There are changes )？
4. say something Hash The consistent algorithm of ？
5. You know GC What are the algorithms and recycling strategies ？GC What is the mechanism of ？
6. The basic principle of garbage collector ？ Whether the memory can be reclaimed immediately ？ How to actively inform JVM Garbage collection ？
7. Parent delegation model mechanism
8. What are the core construction parameters for thread pool creation ？
9. Optimistic lock and pessimistic lock ？ Reentrant locks and Synchronized？
10. Are they all reentrant locks ？ Which is more efficient ？
11. CountDownLaunch and Cylicbarrior The difference between the two and which scenarios are used ？
12. Http and Https And Https Means of encryption ？
13. Future career planning and ideas

Two sides （ Mainly the database , agreement ,Spring etc. ）

1. Self introduction. , Talk about projects that you think you've done well ！
2. InnoDB What are the four supported transaction isolation level names ？ What's the difference ？MySQL What is the isolation level ？
3. Talk about the characteristics of transactions ？ Talk about the analysis of slow queries ？
4. You understand BTree Mechanism ？
5. What are they? MySQL Common optimization methods ？
6. Http Request process ,DNS Analytical process ？
7. Three handshakes and four handshakes ？
8. B+ Tree index and Hash The difference between indexes ？
9. Spring IOC How to manage Bean Dependencies between , How to avoid circular dependence ？
10. SpringBean Design patterns in the creation process ？
11. say something AOP Implementation principle of ？
12. Tomcat What is the basic structure of ？

On three sides （ It's mainly caching , High concurrency , Distributed ）

1. Summary of concurrent experience in my own project
2. say something MySQL Lock concurrency for ？ What is the mechanism of locking ？
3. How to prevent deadlock in high concurrency scenarios , Ensure data consistency ？
4. Cluster and load balancing algorithm and implementation ？
5. Talk about sub database and sub table design ？
6. What are the distributed dilemmas brought about by sub database and sub table and the corresponding strategies ？
7. Redis and Setnx Command how to implement distributed lock ？ Use Redis How to do asynchronous queues ？ What are the disadvantages ？
8. The concept and solution of cache breakdown ?
9. Redis Data structure of ？ Threading model ？ Redis Data elimination mechanism ？
10. Redis The problem of data consistency
11. MQ The realization of the underlying principle ？
12. Block queues without Java How to implement the provided ？
13. Talk about the principle of load balancing ？
14. How to achieve peak clipping in high concurrency environment 、 Current limiting ？

Four sides （ Start with the main project ）

Talk about the middleware used in the project (
Dubbo/MQ/Zookeeper/Redis/Kafka)？

1. Under what circumstances will avalanches occur ？ How to avoid this situation ？
2. Design ideas of high concurrency architecture ？
3. Problems encountered in previous projects and solutions ？
4. What setbacks have you encountered in your life ？ How to solve it in the end ?

Summary

First line Internet companies pay more attention to the ability to solve problems in practical projects , In addition, the interview point is mainly around JVM、 Multithreading correlation 、 The underlying principles of basic knowledge 、 The ability to handle high concurrency . I don't want to talk about interview skills here , Just play it easy , I wish you all a job with high salary and satisfaction ！

Know what it is and don't know why it is , Ali often asks how to review interview skills ？

1、 Popular interview questions and answers

Do your best before the interview , Let your interview success rate improve a bit , Here's a hot one 350 The Internet often asks questions and answers to help you get offer

2、 Multithreading 、 High concurrency 、 Cache entry to actual project pdf Books

book , You can learn by reading It's also good for calming your mind ！

3、 It is mentioned in the article that the answers to the interview questions are sorted out

4、Java Core knowledge interview guide

covers JVM 、JAVA aggregate 、JAVA Multithreaded concurrency 、JAVA Basics 、Spring principle 、 Microservices 、Netty And RPC、 The Internet 、 journal 、Zookeeper、Kafka、RabbitMQ、Hbase、MongoDB 、Cassandra、 Design patterns 、 Load balancing 、 database 、 Consistency algorithm 、JAVA Algorithm 、 data structure 、 Algorithm 、 Distributed cache 、Hadoop、Spark、Storm A large number of technical points and the explanation is very in-depth