In the morning of the first week of July, WHEN I was on the subway going to the company, I suddenly received an interview call from THE HR of PINDUoduo and communicated with me whether I was interested. I expressed my interest, and we arranged the interview time for the first interview. Later, we received the formal interview notice.
Work at his former club for several years, the feeling is met bottleneck, feel slow progress in nearly a year, not used to the rapid growth of a sense of accomplishment, together with his former club business and technology are more stable, so I always want to go out to see opportunities, on the one hand, look at their own strength, on the other hand, want to be able to break through the status quo, continuing on technology progress.
—– Pinduoduo Java R & D post 1234 interview and interview questions —-
One side
- What components do thread pools consist of, what are they, how are they used, and what are the rejection policies
- Write an algorithm that traverses the tree hierarchically and outputs the levels of each layer
- Write a problem, backward traversal of a binary tree, non-recursive algorithm.
- When does a multithread deadlock occur? Write an example
- Let’s talk about the optimization of hashMap and concurrentHashMap in jdk1.8
- How are hash conflicts resolved, and if they occur, how do you find the target value in the hash table
- There are 1000 data in the HashMap, what is the actual number, considering load factors and capacity expansion
- What are the common RPCS? Corresponding differences and performance comparisons?
- Operating system user mode and core state switching conditions and why to switch
- Communication between threads, asynchronous queues, delayed message retrieval
Second interview
- MySQL > create primary/secondary replication
- MySQL index, using B+ tree index benefits
- How to optimize MySQL performance
- How does Redis cache
- Redis persistence operation
- How to use Redis to process hot data
- TCP three-way handshake process, if there is no third handshake what is wrong.
- How to implement distributed lock
On three sides
- Cap? What do you mean by cap
- Network programming niO and Netty related, Netty’s threading model, zero copy implementation
- Is Redis single-threaded or multi-threaded? What does Redis do with distributed clusters?
- What are distributed message queues (Kafka, etc.)? Have you used any? What is the specific application scenario?
- How and why does load balancing work? Know anything about cluster avalanches.
- How to realize peak clipping and current limiting in high concurrency scenarios?
All around (HR)
- Why did you change jobs?
- What are your salary expectations?
- How to treat overtime?
- How do I learn technology? Besides Java, what other technologies do I learn?
- What are your plans for the next few years?
Summary of questions and answers
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