The golden nine silver ten interview is over, I have summarized all the Java job interview questions of all major manufacturers

The golden nine and the silver ten are over, don't you know if you got your favorite offer?
Today, I will summarize the interview questions that you encountered in various major factories, and prepared interview learning materials for everyone at the end of the article

 

Summary of Ali interview questions

1. How to realize the bottom layer of HashMap?
2. Hash consensus algorithm?
3. Talk about the difference between HashMap and ConcurrentHashMap? What is the difference between treemap and HashMap?
4. java memory partition?
5. How to recycle java objects, recycle algorithm?
6. Do CMS and G1 understand?
7. What problem does CMS solve? Tell me about the recycling process?
8. How many times did the CMS recovery pause?
9. When will the java stack overflow? What about the java heap, a scenario?
10. How does the collection class solve this problem (soft reference and weak reference), and what is the difference between these two references?
11. What do you know about locks in java?
12. How to implement the synchronized lock upgrade process (bias lock to lightweight lock and then to heavyweight lock), and what problems are solved?
13. What is the basic architecture of Tomcat?
14. What is a class loader?
15. Talk about the parent delegation model mechanism?
16. What is the mechanism of GC? GC algorithm and recovery strategy?
17. What are the components of the thread pool?
18. What thread pools are there and how to use them? What are the rejection strategies?
19. When does a deadlock occur in multiple threads, write an example?
20. What is the data structure of Redis? What about the threading model?
21. Talk about Redis's data elimination mechanism?
22. Talk about the data consistency of Redis?
23. How to do Redis distributed?
24. What about RPC?
25. Three handshake and four waves? Is there a problem if there is no three-way handshake?
26. Http request process, DNS resolution process?
27. What are the names of the four transaction isolation levels supported by InnoDB? What's the difference? Talk about the MySQL isolation level?
28. The characteristics of the transaction and slow query?
29. What about the BTree mechanism?

Summary of Jingdong interview questions

1. ACID of the transaction, which explains the isolation of the transaction in detail
2. Dirty reading, phantom reading, non-repeatable reading
3. Red-black tree, binary tree algorithm
4. Which collection classes are commonly used? What is the difference between ArrayList and LinkedList? The internal data structure of HashMap? ConcurrentHashMap segment lock?
5. What optimizations have been made to hashMap and concurrentHashMap in jdk1.8
6. How to resolve the hash conflict, and if there is a conflict, how to find the target value in the hash table
7. The difference between synchronized and ReentranLock?
8. ThreadLocal? Application scenario?
9. Java GC mechanism? What are the GC Roots?
10. Will there be deadlocks in MySQL row locks?
11. Do you understand optimistic locking and pessimistic locking? What is involved in optimistic locking and pessimistic locking in JDK?
12. Nginx load balancing strategy?
13. Have you compared Nginx with other load balancing frameworks?
14. Is Redis single threaded?
15. The reason for the high concurrency of Redis?
16. How to use Redis to process hot data
17. Talk about Redis sentinel, replication, cluster
18. What technology has been optimized at work? Talk about JVM, MySQL, code, etc.
19. What does Spring Cloud use? How to achieve load balancing? How to judge if the service is down?
20. Network programming nio and netty related, netty thread model, zero copy implementation
21. What do you know about the implementation of distributed locks? Talk about an implementation method in detail
22. In high-concurrency application scenarios, what does the technology need to involve? How to design the architecture?
23. Next to the issue of high concurrency, it talked about the technical applications of spikes: kafka, redis, mycat, etc.

Summary of Meituan Interview Questions

1. The use and principle of Zookeeper in the project;
2. Introduction to some components of Springcloud;
3. How to create multiple threads
4. What is the relationship between the number of server CPUs and the number of thread pools?
5. Talk about Mysql's sql optimization
6. Redis persistence methods: rdb, aof; which version of redis can be used for distributed use;
7. Nginx usage scenarios;
8. Dubbo timeout retry; Dubbo timeout time setting
9. How to ensure the order of request execution
10. Distributed things and distributed locks (don’t show negative numbers for deductions)
11. Distributed session settings
12. JVM memory model
13. Database split vertically and horizontally
14. How MyBatis pagination; how to set the cache; MySQL pagination
15. Are you familiar with IO? The difference with NIO, the difference between blocking and non-blocking
16. Distributed session consistency
17. The idempotent design of the distributed interface "cannot be deducted repeatedly"

Netease interview questions summary

1. How to ensure service idempotence?
2. The relationship between Kafka data partitions and consumers, Kafka's data offset reading process, how to ensure the order inside Kafka, and how to ensure the order of consumers in combination with external components
3. cms garbage collection mechanism
4. The function of each component of springcloud, internal details, difference from dubbo, dubbo architecture, dubbo load strategy
5. Principle of mapreduce
6. nio,bio,sellector/epoll,aio,netty comes with codec, netty advantage, java memory model
7. akka model
8. java arraylist, linkedlist distinction and implementation principle, hashmap and concurrenthashmap distinction and implementation principle, concurrenthashmap 1.7 and 1.8 distinction, implementation details, linkedhashmap sorting principle, how to ensure data idempotence in applications
9. web.xml listener, filter, servlet loading order. How to load filter without configuring in web and xml
10. Infinite numbers provide multiple plans for topK issues
11. What is the difference between CourrentHashMap JDK1.7 and JDK1.8?
12. Threads a, b, c, and d are running tasks. How to ensure that threads a, b, and c are executed before d thread is executed?
13. .How to ensure data consistency in a distributed system?
14. .Which places should be paid attention to when splitting microservices, and how to split them?
15. What components does SpringCloud Family Bucket contain?
16. Do you know the difference between Docker, Docker and virtual machine?
17. How to communicate between multiple Docker containers on the same host? How to communicate between Docker containers in multiple hosts?
18. How to optimize the performance of high-concurrent systems? How to prevent oversold inventory?

Final summary

After watching so many interviews, I found that the most frequently asked knowledge points for big companies are: JVM principles, multithreading, data structures and algorithms, high concurrency, design patterns, etc. They all say that interviews make rockets, and the big environment is like this. Then you too The rocket must be built well, otherwise there will be no chance to screw the screws. The following are the learning routes and learning materials compiled for everyone:

筑基必备技能：并发编程，JVM，网络编程与高效IO，Mysql，Tomcat

设计思想与开源框架：SSM（Spring+SpringMVC+MyBatis）

性能直线提升架构技术：ZK，Nginx，RabbitMQ，RocketMQ，Kafka，elastic

高效存储让项目性能起飞：Redis，MongoDB，MySQL，Mycat

分布式扩展到微服务架构：SpringBoot，SpringCloud，SpringCloud Alibaba，Docker，K8S

The following information is suitable for middle and senior programmers who have worked for 1-3 years

 

 

 

 

 

 

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