Preface
Today I will share with you the interview history of a big boss from JD.com. After working in a traditional company for three years and 2 months, he finally moved to JD.com and got an offer from a big factory. Study notes at the end of the article !
Jingdong side
1. What are the thread pools used, and what are the parameters of the thread pools, and then ask me a few common thread pool usage and actual scenarios.
2. Knowledge of the collection framework, related knowledge of hashmap, ArrayList, LinkedList source code, basically the whole introduction, and the correlation and difference with hastable, concurrenthashmap
3. Talk about a few garbage collectors, what processes does the cms collector have, and if there are several pauses, will memory fragmentation occur? What is the problem with memory fragmentation in the old age?
4. Talk about quick sort and analyze the time complexity?
5. An introduction to the parent delegation model
6.Synchronization and volatile keyword in java
7. JVM memory partition, why should there be a new generation and an old generation
8. Is there a VM memory optimization?
9. What is the difference between a database index primary key and a unique index
10. What is the difference between a clustered index and a non-clustered index?
11.The difference between MySQL storage engine innoDB and MylSAM?
12. What does the Data field of the leaf node of the innoDB B+ tree index store? Does the Data field of the leaf node of the B+ tree index of MylSAM store the primary key or the physical address?
Jingdong two sides
1. What is the difference between the b+ tree index, primary key index and clustered index of MySQL innodb.
2. Four characteristics of the database
3. The four isolation levels of transactions
4. Jvm scene problem, memory fragmentation occurs in the old generation after the mark is cleared many times, causing full gc, what problems may happen next.
5. What are the locks in MySQL, row locks, table locks, and optimistic locks?
6. How does the MySQL deadlock occur? Two examples are given.
7. What does zookeeper in dubbo do
8. Understanding of aio, nio, bio, what are the core concepts of NIO?
9. What are the commonly used NIO frameworks? Advantages and disadvantages
Jingdong three sides (director side)
1. How does redis guarantee thread safety in distributed mode
2. Redis persistence method and difference
3. How does zookeeper implement distributed locks and how other distributed locks implement 4. Kafka's architecture and how to use Kafka to ensure the orderliness of messages
5. What is the optimization of the database? MySQL optimization, talk about two examples of your optimization.
6. For the most technically difficult project, introduce the relevant core design process.
7. At work, if you encounter a technical bottleneck that cannot be solved, what is your solution?
8. What is your future career plan?
to sum up
The success of the boss is not achieved overnight, but the hard work has been done behind the scenes. From the subsequent chat process, I learned that learning alone is more than others!
Finally, I will share the interview information of the boss with everyone for free, I hope it will be helpful to everyone
Data collection add assistant vx: bjmsb03
I heard that all the fans of the one-click three consecutive interviews succeeded? I also wish all readers can get their favorite offers!