Introduced 4 aspects of Ali's Java technology post: JVM memory structure + (multi-threading, thread pool, etc.) + performance optimization + Spring framework + consistent Hash algorithm + microservice distributed, etc.

Key points of Java job interview:

Data structure and algorithm, JVM memory structure, garbage collector, recycling algorithm, GC, concurrent programming related (multithreading, thread pool, etc.), NIO/BIO, performance optimization, design pattern, Spring framework: distributed related: Redis cache, Consistent Hash algorithm, distributed storage, load balancing, etc., microservices and Docker containers, etc. Due to a lot of text, I have summarized the frequently asked questions and frequently asked interview questions involved in java interviews and shared them with you for free

Interview: If you do not prepare for an adequate interview, it will be a waste of time and you will be irresponsible for yourself.

 

One side (one hour and ten minutes)

1. Introduction

2. Tell me about the difference between B+ tree and B tree, advantages and disadvantages, etc.?

3Talk about Spring, main IOC, etc.

4 Some common classes under the multi-threaded JUC package, such as CountDownLatch, Semaphore, etc.

5. The concept of lock, lock-related keywords, volatile, synchronized. Also compares ReentrantLock and synchronized.

6. Which collectors do you know? CMS and G1. Talk about the advantages of G1 in detail? When will Full GC be performed?

7. Some design patterns involved in Spring

8. Algorithm question: find the k-th largest number in the unordered number sequence (maintain the smallest heap, then traverse sequentially, and compare with the top of the heap)

9. MySQL index creation principles, benefits

10. How to implement a thread-safe counter?

Two sides (more than forty minutes)

1. Design pattern: talked about singleton, factory method, abstract factory, strategy pattern, observer pattern, agent pattern, and by the way, the implementation principle of spring dynamic agent

2. What are the parameters of the thread pool? What is the use of each? What happens if the number of tasks exceeds the number of core threads? What is the blocking queue size?

3. The underlying data structure of HashMap

4. The specific structure and implementation of the red-black tree, and the difference between the red-black tree and the search tree

5. Then talk about ConcurrentHashMap, the underlying implementation

6. Understanding of HashMap hash function, the hash function used by JDK1.8

7. Database index, the realization of the underlying index, the structure of the B+ tree and the advantages of the ordinary search tree

9. The TCP three-way handshake waved four times, what kinds of states and packets were on the server during the four waved hands

10. There is already an interface for querying friends. Design a WeChat Moments, which can realize functions such as posting Moments, adding comments, and viewing comments. Mainly design data structure

Three sides (50 minutes: the main distributed one)

1. What do you know about Kuaishou, the difference with Douyin, talk about projects
2. Dubbo is used in the project? Then what are you talking about rpc framework? What is the difference with http call?
3. What data structure does Redis have? Persistence scheme and difference?
4. Redis sentinel and cluster design principles and differences?
5. Will there be consistency issues between Redis cache and database? How to deal with it
6. How does Kafka guarantee data reliability? Talking about the at-least-once and at-most-once for the consumer to send messages to the broker for persistence, partitioning and replication mechanisms? How to achieve Exactly-Once?

HR surface:

1. What is your personal greatest weakness?
2. What is the biggest challenge encountered in work and life? How was it overcome?
3. What are the plans for the future?
4. What are your hobbies

The regular interview process is mainly about your own strengths and weaknesses, your future career development, and salary.

At last

In response to the above interview questions, I summarized most of the interview questions and answers involved in the Internet company java programmer interviews. Documents and architecture video materials are shared for free (including Dubbo, Redis, Netty, zookeeper, Spring cloud) , Distributed, high concurrency and other architecture technical materials), hope to help you review before the interview and find a good job, and also save everyone's time to search for materials on the Internet to learn. Use every minute and every second of your time to learn to improve yourself, and don't use "no time" to conceal your mental laziness! While you are young, work hard and give your future self an explanation! At the end of the article, share the structure information, and private message [structure] to receive free access !

 

kafka：

 

Spring principle: