Fight a lot on all sides, take the offer back to share the interview experience summary

Speaking of the beginning of the interview, it was the morning of the first week of July. I was still on the company’s subway and suddenly received an interview call from Pinduoduo HR. I communicated with me if I was interested. I expressed interest and agreed with each other. At the first interview time, you will receive a formal interview notice later.

I have been working for my old club for a few years, and I feel that I have encountered a bottleneck. I feel that progress has been slow in the past year. I don’t have the sense of accomplishment of rapid growth in the past. In addition, my old club’s business and technology are relatively stable. On the one hand, I look at my own strength, on the other hand, I hope to break through the status quo and continue to advance in technology.

-----Pingduoduo Java R&D post 1234 interview process and interview questions----

 

one side

1. What are the components of the thread pool, which thread pools are there, how to use them, and what are the rejection strategies
2. Write an algorithm to traverse the tree level and output the level of each level
3. Write a question, post-order traversal of binary tree, non-recursive algorithm.
4. When will deadlock occur in multithreading, write an example
5. Talk about the optimization of hashMap and the optimization of 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. There are 1000 data stored in the hashmap, what is the actual number, considering the load factor and expansion
8. What are the common RPCs? The corresponding difference and performance comparison?
9. Operating system's user mode and core mode switching conditions and why they need to be switched
10. Communication method between threads, asynchronous queue, delayed message acquisition

Two sides

1. How to do MySQL master-slave replication
2. MySQL index, the benefits of using B+ tree index
3. MySQL performance view and how to optimize
4. How does Redis cache
5. Redis persistence operation
6. How to use redis to process hot data
7. The TCP three-way handshake process, if there is no third handshake, what is the problem.
8. How to implement distributed locks

Three sides

1. Do you know cap, what do you mean?
2. Network programming nio and netty related, netty thread model, zero copy implementation
3. Is Redis single-threaded or multi-threaded? How to do Redis distributed cluster?
4. What are the distributed message queues (Kafka, etc.)? Which ones have you used? What specific application scenarios?
5. How do you do load balancing, why do you do it? Have you ever learned about cluster avalanches?
6. Talk about the realization of peak shaving and current limiting in high concurrency scenarios?

Four sides (HR)

1. Why quit?
2. What is the expected salary?
3. How to treat overtime issues?
4. How do you usually learn technology, besides Java-related, what other technologies will you learn about?
5. What are the plans for the next few years?

Summary of questions and answers

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