Undergraduate six years, Ali technical three + HR, won 38*16 Koffer, grade P7

Preface

Summary of the face from a four-faced Ali

I think there is an idea of ​​being able to find an offer from a major manufacturer. This is normal. This is not our after-dinner talk but the pursuit of every technical person. The technical atmosphere and technical standards of Alibaba, Tencent, Meituan, ByteDance, JD, etc. are still significantly better than some entrepreneurial companies/small companies. If you can practice in such a company for several years, I believe that you can The improvement is still very large. Whether it is school recruitment or social recruitment, various interviews and written examinations cannot be avoided. How to prepare for these things is extremely important. Whether it is a written test or an interview, there are rules to follow.

Because interviews at major companies are usually conducted by professional teams, whether you have mastered a certain knowledge point or simply memorized it, the interviewer can tell when you ask (PS: It’s really the interview, especially when you feel that there is not enough time to prepare for the interview. , You can pick some of the frequently asked questions in interviews, pay attention to understanding, and be sure not to memorize them). Don't place too much hope on all kinds of experience, try to improve your comprehensive ability.

The phrase "80% of offers are in the hands of 20% of the people" is not unreasonable. Although strength occupies a large proportion of the factors that determine your success in the interview, if you have bad mentality or bad luck, you still cannot get a satisfactory offer. Aside from luck, let’s take the mentality as an example. Don’t be discouraged or doubt your abilities because of the interview failure. After the interview fails, sum up the reasons for the failure. Later you will find that you will become stronger and stronger.

What are the frequently asked techniques in Ali interviews

Data structure, multi-threading, jvm, Spring, optimization, message framework, distributed, cache, etc. and the framework you have used and the foundation of the first round is very important. The possibility of admission after the meeting is relatively high!

One side (mainly jvm, concurrency, lock, data structure, etc.)

1. Self-introduction (talk about one's good at and skills)
2. Talk about the difference between treemap and HashMap? The difference between HashMap and ConcurrentHashMap?
3. How to realize the bottom layer of HashMap (with JDK1.8 changes)?
4. Talk about the consistent algorithm of Hash?
5. What GC algorithms and recycling strategies do you know? What is the mechanism of GC?
6. The basic principle of the garbage collector? Can the memory be reclaimed immediately? How to actively notify the JVM for garbage collection?
7. Parental 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. The difference between CountDownLaunch and Cylicbarrior and in which scenarios are they used?
12. What is the difference between Http and Https and the way of Https encryption?
13. Future career plans and ideas

Two sides (mainly databases, protocols, Spring, etc.)

1. Introduce yourself and talk about projects that you think are well done!
2. What are the names of the four transaction isolation levels supported by InnoDB? What is the difference between? What is the MySQL isolation level?
3. Talk about the characteristics of the transaction? Talk about the analysis of slow queries?
4. Do you understand the BTree mechanism?
5. What are the commonly used optimization methods for MySQL?
6. Http request process, DNS resolution process?
7. The process of three-way handshake and four-way handshake?
8. What is the difference between B+ tree index and Hash index?
9. How does Spring IOC manage the dependencies between Beans and how to avoid circular dependencies?
10. Design patterns in the creation of SpringBean?
11. Talk about the realization principle of AOP?
12. What is the basic architecture of Tomcat?

Three sides (mainly caching, high concurrency, distributed)

1. Concurrency experience summarized in your own project
2. Talk about MySQL lock concurrency? What is the locking mechanism?
3. How to prevent deadlock and ensure data consistency in high concurrency scenarios?
4. Algorithm and implementation of clustering and load balancing?
5. Talk about sub-library and sub-table design?
6. What are the distributed dilemmas brought by sub-databases and sub-tables and corresponding strategies?
7. How do Redis and Setnx commands implement distributed locks? How to use Redis for asynchronous queue? What are the disadvantages?
8. The concept and solution of cache breakdown?
9. Redis data structure? Thread model? Redis's data elimination mechanism?
10. Redis data consistency problem
11. The realization of the underlying principles of MQ?
12. How to implement blocking queue without Java?
13. Talk about the principle of load balancing?
14. How to achieve peak shaving and current limiting in a high concurrency environment?

Four sides (start with the main project)

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

1. Under what circumstances will cause an avalanche? How to avoid this situation?
2. Design ideas for high-concurrency architecture?
3. Problems encountered in previous projects and their solutions?
4. What setbacks have you encountered in your life? How was it solved in the end?

summary

First-tier Internet companies pay more attention to the ability to solve problems in actual projects. In addition, the interview points mainly focus on JVM, multithreading, basic knowledge of the underlying principles, and the ability to handle high concurrency. I don’t talk about interview skills anymore, just play it easily. I wish you all a high-paying and satisfying job!

Knowing this and not knowing why, Ali often asks how to review interview techniques?

1. Popular interview questions and answers

Do enough work before the interview to increase your interview success rate. Here is a popular 350 first-line Internet frequently asked interview questions and answers to help you get an offer

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2. Multithreading, high concurrency, cache entry to actual project pdf book

Books, reading can not only learn but also help calm the mind!

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3. The answer to the interview questions mentioned in the article is organized

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4. Java Core Knowledge Interview Collection

Covers JVM, JAVA collection, JAVA multi-threaded concurrency, JAVA basics, Spring principles, microservices, Netty and RPC, network, log, Zookeeper, Kafka, RabbitMQ, Hbase, MongoDB, Cassandra, design patterns, load balancing, database, consistency A large number of technical points of sexual algorithms, JAVA algorithms, data structures, algorithms, distributed caches, Hadoop, Spark, and Storm are explained very in-depth

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Interview Collection + Books + Core Knowledge Acquisition: Forward + Follow Add Assistant VX: MXW5308 can get it for free