Ant Financial (Five Sides)
one side
At the same time, I did an algorithm problem and required it to be completed within two hours. I gave an array of length N with repeated elements and asked to output the 10th largest number. The typical TopK problem is solved by the quick sorting algorithm.
Algorithmic questions should pay attention to the legality check, boundary conditions and abnormal handling. In addition, if you want to write test cases, you must ensure that the test coverage scenarios are as complete as possible. In addition to the usual brushing algorithm questions, this kind of assessment should be no problem.
Two sides
- Introduce yourself
- Have you contributed code to an open source project?
- What does the department currently do, what are the internal systems, functions, and interaction processes?
- What pits have Dubbo stepped on and how did they solve them?
- Start to get into the topic, talk about your understanding of thread safety
- What are the characteristics of transactions?
- How to understand atomicity?
- The difference between optimistic lock and pessimistic lock?
- How are these two types of locks implemented in Java and MySQL?
- Why is HashMap not thread-safe?
- How to make HashMap thread safe?
- What is the difference between the synchronize of Collections?
- What optimizations has been made to ConcurrentHashMap in jdk1.8?
- Do you understand the redis master-slave mechanism? How did it happen?
- Have you had any experience in GC tuning?
- Is there anything you want to ask?
Three sides
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Briefly introduce yourself
- How does the monitoring system work, which modules are divided into, and how do the modules interact? What database is used?
- What storage engine is used, and why use InnnoDB?
- Is the order form split? How to split it?
- The query process description after horizontal split
- What if the data that falls into a certain shard is large?
- Is there any problem with hash modulus?
- How to solve the pressure of reading and writing after sub-database and table
- How to ensure that the primary key is unique after splitting?
- Is the ID generated by Snowflake globally incremented and unique?
- How to achieve a globally incremented unique ID?
- Mysql index structure
- What is the difference between a primary key index and a normal index?
- Where is the current bottleneck of your system?
- How do you plan to optimize? Briefly talk about your optimization ideas
- Is there anything you want to ask me?
All sides
- Introduce yourself
- Why do reverse engineering?
- How to understand microservices?
- How is service governance achieved?
- Isn't this something middleware does? Why does your department do it?
- Talk about the life cycle of Spring
- Talk about the process of GC
- What's wrong with CMS GC?
- How to avoid floating garbage?
- What's the problem with forcing young gc?
- Do you know G1?
- What is the recycling process?
- How is the bottom layer of Remember Set you mentioned?
- Is there anything you want to ask?
Five sides
Five faces are for HRBP. I made an appointment with me in advance, mainly talking about my previous internship experience at Ant, what the department is doing, career development, welfare benefits, etc. Ali interviewers do have one-vote veto power, and they value whether your values match or not, and generally prefer candidates who are honest. HR must be honest, don’t lie, as long as you lie, HR will verify it and cut it directly.
- Why didn't Ant stay after three months of internship?
- Who was the supervisor during the internship?
- What did the internship do?
- What do you think of technology? What technology stack do you usually use?
- Have you been researching anything recently?
- What do you think of SRE
- Do you have any expectations for the treatment?
Finally, HR also told me that there is a shortage of people in the stability protection department, and I hope I will reply as soon as possible.
summary
Ant interviews pay more attention to the basics, so the basic skills of Java must be solid. Ant's working environment is quite good, because I am in front of the stability assurance department, and there are many separate groups, like Class 1 for three years, which is very youthful. The basic level of the interviewers is relatively high, basically P7 or above, in addition to the basics, they also asked a lot of questions about the architecture design, and the harvest was quite big.
Pinduoduo (three sides)
Before the interview
After facing the ants, I had already heard about the unicorn of Pinduoduo, so I decided to go there too. First of all, I found a Pinduoduo HR in Maimai, added a WeChat chat, and sent my resume to start my Pinduoduo interview journey. I would like to thank Miss Pinduoduo HR for helping me from the interview to the offer confirmation. She is really nice.
one side
- Why did the ants only stay for three months? Didn't get regular?
- Explanation of HashMap and TreeMap in Java?
- What is the time complexity of TreeMap query writing?
- What's wrong with HashMap multithreading?
- What is the difference between CAS and synchronize? Isn't it possible to use synchronize?
- What if you want to ensure thread safety? (ConcurrentHashMap)
- How does ConcurrentHashMap achieve thread safety?
- Does get need to be locked and why?
- What is the role of volatile?
- How is the bottom layer implemented?
- How to ensure visibility under multi-core CPUs?
- Talking about the project, how do the systems interact?
- How much concurrency is in the system and how to optimize it?
- Give me a piece of paper, draw a nine squares, fill in the numbers, give an MN matrix, and print the MN numbers counterclockwise starting from 1, requiring the time complexity to be as low as possible
- You can talk about your thoughts first (remembered, when to say when to change the direction of the conditions, to the right, down, left, up, and so on)
- What do you want to ask me?
Two sides
- Introduce myself
- Do you have any other offers?
- What is the organizational structure of the department?
- What are the modules in the system, what technologies are used in each module, and how does the data flow?
- How is the link tracking information transmitted?
- How does SpanId guarantee uniqueness?
- In what dimension is RpcContext passed?
- How is Dubbo's remote call implemented?
- How is Spring's singleton implemented?
- Why implement a service governance framework separately?
- Who is leading? Is it still in use internally?
- Have you ever thought about how to make it universal?
- Is there anything you want to ask?
Three sides
After the face of the second boss, he directly interviewed the HR, mainly asking about career development, whether there are other offers, and the intention to enter the job. By the way, the company's benefits and benefits are more conventional. But what I have to say is that if you have other offers or experience with big factories, you will get some bonus points.
summary
Pinduoduo's interview process is much simpler, after all, it is a company that has been established for more than three years. The difficulty of the interview is moderate, as long as the foundation is solid, it shouldn't be a problem. But I have to say that the work intensity is very high. Before the start of the interview, HR confirmed with me in advance whether I can accept such an intensity of work. The old iron who wants to come must be prepared.
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