Summary of the latest interview experience of many large companies such as Ali, Baidu, Jingdong in 2021

Preface

Many Java developers may not have long working hours or rich work experience before the interview, so I don't know what questions Internet companies or first-line Internet companies will ask in technical interviews.
In addition, I may not be fully prepared. I was overwhelmed by a few questions by the interviewer within a few rounds of the interview and ended in a disastrous defeat.
In response to these, I have collected and sorted out the interviews of some well-known big companies, and shared them here for your reference, so that readers who are about to interview or have ideas to change jobs will understand which questions they like to ask during interviews with first-line big companies~

Let's start to get to the point~

Pinduoduo (three sides)

 

one side

1. Briefly introduce yourself.

2. How to configure SpringBoot?

3. Where can the application.properties and application.yml files be placed? Priority?

4.The principle of SpringBoot automatic configuration?

5.How does SpringBoot modify the port number?

6.How many ways to enable SpringBoot features?

7. Which endpoint is accessed to obtain Bean assembly report information?

8. Describe the processing flow of the thread pool?

9. How to activate the configuration of a certain environment?

10. Is there any solution for SpringBoot to read the configuration?

11.How does SpringBoot modify the port number?

Two sides

1. Please describe the workflow of Spring MVC?

2. Describe the workflow of DispatcherServlet?

3. What is MVC? What are the benefits of the MVC design pattern?

4. Which annotation of the controller in SpingMvc generally uses, and is there any other annotation that can be substituted?

5. The role of @Controller annotation.

6. The role of @ResponseBody annotation.

7. How does Spring MVC set up redirection and forwarding?

8. How do Spring MVC and AJAX call each other?

Three sides

1. Explain the JVM memory model in detail.

2. Why should JVM memory be divided into new generation, old generation and persistent generation. Why is the new generation divided into Eden and Survivor.

3. Why is it divided into Eden and Survivor? Why are there two Survivor areas?

4. What is a complete GC process in JVM and how to promote the object to the old age.

5. How much do you know about the relevant knowledge of the JVM memory model, such as reordering, memory barrier, happen-before, main memory, and working memory.

6. Finally, talk about the projects you have participated in, those with relatively high technical content, related architecture design and what core coding you are responsible for.

 

Ali (three sides)

 

MySQL+Redis+message middleware+Zookeeper+microservice

one side

1. What are the differences between MyISAM and InnoDB**?

2. What are the characteristics of MySQL transaction isolation levels?

3. What MySQL index related optimizations have been made.

4. Briefly talk about the database paradigm.

5. How to page query for a table with 10 million data?

6. How to deal with the slow query due to the increasing amount of data in the order table?

7. What are the components of MySQL and what are they used for?

8. What are the drawbacks of MySQL query cache, under what circumstances should it be used, and what changes does 8.0 version have to query cache?

9. Is unique index faster than normal index and why?

10. How does MySQL restore the data half a month ago

Two sides

1. What are the advantages of Redis over memcached?

2. Which data types does Redis support?

3. What kinds of data elimination strategies does Redis have?

4. Why does Redis need to put all data in memory?

5. What should the Redis cluster solution do? What are the options?

6. Under what circumstances will the Redis cluster solution cause the entire cluster to be unavailable?

7. What are the suitable scenarios for Redis?

8. What is the relationship between Redis and Redisson?

9. What are the advantages and disadvantages of Jedis and Redisson?

Three sides

1. Introduction

2. Participate in concurrent projects, from design to deployment, follow the process.

3. How to realize database master-slave synchronization and how to realize transactions?

4. What are the similarities and differences between the Ali-based middleware metaQ and its principles and the existing Kafka?

5. Do you know any middleware in Ali? Implementation principle? What are the characteristics of other open source message queues?

6. What are the types of Znode?

7.What are the several deployment modes of Zookeeper?

8. Is Zookeeper's watch monitoring notification to the node permanent? Why not?

9. What is the working status of Server under Zookeeper?

10. Talk about your understanding of SOA and microservices, as well as the adjustments and challenges involved in distributed architecture from the application level.

11. Three to five years of career planning? What do you want to ask me?

 

Today's headlines (three sides)

 

One side (50 minutes)

1. What are the basic components of Linux?
2. Why is the Linux architecture divided into user space and kernel space?
3. What is the basic difference between BASH and DOS?
4. What system log files does Linux have?
5. Java GC mechanism? What are the GC Roots?
6. Red-black tree talk about five features, insert and delete operations, time complexity?
7. Hashmap, how to expand, how to deal with data conflicts? How to efficiently implement data migration?

Two sides (40 minutes)

1. Introduce yourself and talk about your area of ​​expertise.
2. Explain the redis data structure.
3. How much do you know about design patterns?
4. What is the difference between the three agents in the design pattern?
5. When to use HashMap and when to use ConcurrentHashMap?
6. Why is Java 8 more efficient at concurrency?

Three sides (about 1 hour)

1. The realization of MySQL index, innodb index, how to realize the b+ tree index, why use b+ tree as index node, how much data a node stores, how to specify the size, corresponding to the disk page.

2. If Redis has 100 million keys, will using the keys command affect online services?

3. How many roles does the builder mode usually include?

4. Talk about the code implementation template method pattern.

5. How is MySQL data master-slave synchronization achieved?

6. What is the future plan?

7. Do you have anything to ask me?

Jingdong (three sides)

 

Spring Cloud + seckill + Redis

one side

1. Brief self-introduction.

2. What optimizations have been made to hashMap and concurrentHashMap in jdk1.8?

3. What is the difference between synchronized and ReentranLock?

4. ThreadLocal? Application scenario?

5. Will there be deadlocks in MySQL row locks?

6. ACID of the transaction, which explains the isolation of the transaction in detail.

7. ThreadLocal? Application scenario?

8. What is the difference between ArrayList and LinkedList?

9. Tell me about the implementation principle of HashMap?

10. Speaking of red-black trees, what is a binary tree first?

Two sides

1. Talk about Redis sentinel, replication, cluster?

2. Is Redis single threaded?

3. What are the basic components of Linux?

4. What is the inter-process communication method used by Linux?

5. What are forward proxy and reverse proxy?

6.What attribute modules does the Nginx configuration file nginx.conf have?

 

7. How to use Nginx to solve the front-end cross-domain problem?

8. What technology has been optimized at work?

Three sides

1. What modules do Spring consist of?

2. What design patterns are used in the Spring framework?

3. Explain in detail the core container (spring context application context) module.

4. What are the different components of a Spring application?

5. For high concurrency application scenarios, what are the technical requirements involved? How to design the architecture?

6. Finally, talk about the projects you have participated in, those with relatively high technical content, related architecture design and what core coding you are responsible for.

 

At last:

In view of the fact that many people have been interviewing recently, I have also compiled a lot of interview topic materials here, as well as experience from other major companies. Hope it helps everyone.

 

I also sorted out some interview materials & the latest real interview questions from some big companies in 2020 (all organized into documents, a small part of the screenshots), if you need it, you can: add VX: mxj94670 to get it!