Let’s talk about the background of the interview: about 10 days ago, I received an interview call from Meituan HR, saying that it was the final exam, and I was going to go, but the company’s project was in a hurry the day before the interview appointment, so I replied The email canceled the interview; after a week on Wednesday, HR called again to discuss the interview time, and then decided on Thursday; on the 18th, that is, Thursday, I received a call from HR again. After resigning, I agreed to an interview at 10 am on Friday.
I arrived at Hengdian Building in Wangjing R&D Park at about 9:50 on Friday. About 10 minutes later, HR took me to the conference room on the 7th floor. After waiting for about a quarter of an hour, the interviewer came in. The following is the interview content:
1. Implementation of Redis transaction mechanism and LRU algorithm; design data structure by yourself to implement LRU (double-ended queue, dynamic adjustment (added later), elimination from the end of the queue, over)
2. The implementation principle of hdfs and how to ensure that data is not lost (NameNode, secondaryNameNode, DataNode, fsimage+editlog, too)
3. mongodb storage structure, usage scenarios, gridfs, use cases (for simple business reasons, I have only used the stand-alone version, but I have studied distributed, and the interviewer is not very satisfied)
4. mysql lock level, clustered index, index principle (the answer was B+ number at the time, which was a bit confusing), usage scenario description
5. The process of SpringMVC, after the answer, I asked a friendly display to the user about how to deal with the problem of the background service (I replied that I could redirect to a new page, he was not satisfied, and later said that the prompt was Aop, and immediately I feel that communication is not only a problem, but hurts 100 points. I know it clearly, but I didn't say it.)
6. JVM command tuning, how to find the system performance bottleneck and improve it (I didn't use it much, I only remember jstat, I was afraid to ask in depth, I only said that I have used jconsole to monitor, the use of commands, this part is lacking, I feel the whole process When the interviewer was dissatisfied, the atmosphere began to change, but fortunately, the answer below was ok, which saved part of it.)
7. Basic algorithm (binary search problem of handwritten ordered repeated array, you need to pay attention to finding the first one of repeated elements, parameter verification, simpler)
8. Principles of synchronize, Lock, and volatile (I was asking about using it to modify a variable. The change of memory is a bit confusing. After answering, the interviewer said, aren’t you talking about CAS? Second death, the atmosphere is a bit embarrassing, hurry up Apologize that maybe I don't remember well, I need to review something.)
9. ReadWriteLock, ReentrantLock (asked about the difference with synchronize, the answer is quite satisfactory, there is no disclosure, the atmosphere begins to relax)
10. GC algorithm and collector (basic algorithm, CMS collector principle, and later to the G1 collector, the interviewer did not give a chance. I have been listening quietly throughout the whole process, I feel more satisfied)
Later, I asked a small question and it was all ok. Also made me ask some questions. At about 11:23, the interview was over, and they told me to wait. I responded without saying anything else. The interviewer went out for a quarter of an hour and someone knocked on the door. He directly said that I was more suitable for infrastructure from resume to actual mastery. They are financial service platforms, doing business, and there is no matching position for me. He suggested that I apply for other departments. When I got here, I was quite confused. The resume was asked by their technical manager on a certain platform. The phone number was called (many times) by them. The interview was also strictly based on the resume. The position was given to me, since the resume is not suitable, why asked me for an interview, and why did I interview according to the resume, which made me doubt the goodwill of Meituan, and suspected that there was a problem in the communication between their R&D department and the human resources department, which affected me. pond fish. But after all, I also found some shortcomings of my own, which are also valuable.