Dachang face-to-face sharing-let's talk about my Alibaba Cloud P7 interview experience

background

  This article is to record some of the interview experience in my work history, and also hopes to be a reference for those children who want to understand the situation of large factories. This article comes from personal experience. Some parts may be different from the experience you have acquired before. Please use it as a reference.
  I am facing the Alibaba Cloud back-end storage development post, rank P7. It took about three weeks to go through three rounds of technical skills, one written test, and one boss interview. Let me share my interview experience based on the order of the interview.

One side: resume interview

  If the interview feels that the resume is suitable, I will first talk to you about the project described in the resume. It can be regarded as getting your bottom line to see if you meet the hiring position and whether the corresponding rank is satisfied. Therefore, this interview will generally not ask too much about the technical details of the project, and both parties will have a broad conversation. It mainly includes the aspects of your project and project design, and you can also talk about the technical situation involved in the position you are applying for. As far as I know, this interview will usually be arranged by your future supervisor (unless he has no time).
  This time I met with a female supervisor. She is very talkative and has a clear thinking. The main focus is on what I have done before. For example, what is the role played in the storage project and how to solve the key problems. Because my personal development path is not entirely a technical post, she focused on asking me how I considered switching from non-technical technology and how I plan to develop in the future. She also specially reminded me that HR will definitely ask this question later. My answer here is quite good. I said that I think technology is better for personal growth. Many Internet companies are managed by technology, and there is no so-called pure management. The interviewer also asked me about some of the technologies used in my business, such as how the three-copy storage guarantees the reliability and consistency of the data. These are some basic knowledge points, only discussed, and did not discuss the details in depth, so the overall interview is not very stressful. I talked about rectification for about an hour. The interviewer said mostly. I kept telling me about the index-level business they did. If the interviewer is actively introducing you to the business, then this is a better signal to show that he treats you. It is more recognized. At this time, you can relax and communicate with each other more easily.

Two sides: basic technical side

  This round of interviews is a discussion of real technical details. I arranged for the second side after about a week. The second interviewer is a newly promoted P8. He used to have a background of Chrysanthemum Factory. It happened that the background was similar to mine, so it was very speculative to chat. He asked me a few technical details and elaborated on them one by one. First of all: talk about how to ensure data reliability and consistency in the storage products you make. Here I start from the three replicas, how to distribute the three replicas to ensure disk-level, node-level and cabinet-level reliability, and then use the NRW algorithm, while taking into account the performance of the data update. Also talked about the vector clock algorithm to ensure the processing of data write conflicts. Finally, I talked about how to distribute EC algorithm data to ensure data reliability. The answer to this question is relatively comprehensive, and the interviewer is quite satisfied. In the process of communication, I mentioned that I used to attack the friend-seller’s writing amplification problem that was mentioned by the friend in the bidding competition test. He asked us how to improve the performance of the small IO on this question. The classic data structure LSM tree used for this problem. In the next article, I will specifically talk about LSM tree.
  This round of interviews actually guided the interviewer a bit, I took the initiative to guide the topic, and then the interviewer followed the train of thought. For the third question, let me talk about how the distributed system chooses the master. I will talk about the raft algorithm carefully, focusing on the process from the master failure to the new master generation and data compensation. The answer to this question is also quite satisfactory. The last question is whether we have temperature and cold data, and whether the system can automatically identify the temperature and cold data and perform relocation. I directly answer this question. We are manually triggered by the user, and the system does not automatically recognize it. I felt that the process went smoothly during the whole two-sidedness. It was all things I made and familiar things. Finally, the interviewer and the interviewer touted each other and ended the process. The entire interview process took about an hour.

Three sides: intersection

  In the third round of interviews, Alibaba Cloud looked for people from other teams to do an intersection. It was about three days after the two sides. The whole interview process is not actually smooth. I felt it right from the beginning of the interview, because the interviewer is a purely technical person, and the communication is very straightforward, without any euphemisms and skills. He asked me how the asynchronous replication in the project achieves the consistency between the main and the standby. In fact, this mainly uses log replication, how to restore the checkpoint point, and then talks about how the RPO 5 minutes is achieved. The second question is how the stripe writing process of EC (Erasure Code is, how to deal with the stripe dissatisfaction? Is it always in the memory? I did not answer this question, in fact, the data is mixed in the cache. , That is, several irrelevant data can be formed into a full strip to store, because the data in EC format, the data access unit is one EC block, not according to the dimension of the object. Later, let us introduce the entire IO path The process is in the system storage process. I just
  give a general description of this. Finally , I gave a written test question, which was sent to me by email, which is actually a link to Ali’s internal written test platform. The question is like this: Sum the numbers: 1->2->3+4->5=1->6->8 (123+45=168) Let’s talk about the idea first, and then let’s start to do the problem, and finish it in half an hour In fact, the key to this question is to think of inverting the linked list and then adding up the digits to the third linked list in a linked list. Children's shoes who want answers to the
  written test questions, remember to follow me and leave a message. After this round of interviews are over At one time, I thought it was out of play. Fortunately, I asked the person in charge of the referee to find out that the interview was okay. Let me wait for the boss to meet. So sometimes it’s still important to have someone inside.
  I didn’t think I had a good answer in this round of interview . The interviewer failed to adjust his mentality in time when he felt unsatisfactory in communication. The whole process did not guide the interviewer like the two sides. In fact, he can guide the interviewer to talk about the multiple copies and the raft algorithm that he is good at. The rogue was in a bad state at the time. Did not get the upper hand.

Four sides: Boss side

  Boss has better luck with noodles. The interviewer is my former senior colleague in Juchang, but they didn't know each other well when they were in Juchang. The whole interview process was actually very warm. I had lunch together and then went to chat. We talked about people we met before and the current business distribution. Finally, he asked a few questions related to the interview: 1 The three things you thought were right in the company before and the three things you didn't think were done well. Are you familiar with KV storage, and what are the commonly used algorithms? These issues can be positive.

to sum up

  The above is my interview experience. Although everyone's interview experience is different, I still hope that my interview mentality can be used for your reference. Finally, I wish you all find a good job during this period of three golds and four silvers!