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The article is the first for a company that give me an interview, when receiving the interview invitation didn’t hope too much, it is universally acknowledged that the universe article algorithm theory, algorithm, this is the weakest part of myself, but I didn’t think all the way into the three sides, a little trembling, after the three face the interviewer said to communicate with the other two interviewers after can give me the result. Let’s take a look at what they asked. I recorded them for the purpose of writing the interview.

The first side

The interviewer was punctual, a handsome guy of the little brother next door type, probably just woke up with a casual haircut but good looks. He was online at 2pm sharp, yawned and started the video interview, which lasted 1 hour and 28 minutes and was very basic.

  1. To introduce myself
  2. What is a database index for

Here I answered the questions about index type, underlying storage, query efficiency

  1. Why use B+ tree storage

Here is a comparison with the red-black tree, and then the operating system file system’s page-relevant answer

  1. What are the database paradigms, and why do they exist

Three paradigms concept said, and then from the design of the answer why there

  1. Mysql database underlying storage

In terms of storage engines

  1. Database type, relational database what else?

Explain the advantages and disadvantages of typical relational, document, mysql, mongodb, hbase, Redis, and ES

  1. Tell me about the JVM, how do you understand memory leaks

From the virtual machine parameters tuning, virtual machine function (I got a little excited at the end of the talk, I said this is the flying soul of Java, we all laughed)

  1. Garbage collection mechanism, garbage collection algorithm to explain, how to judge is the old age, trigger garbage collection when

This spoke for a long time, spoke of the more detailed, he later asked me from where to learn, I put Zhou Zhiming that “in-depth understanding of the JVM virtual machine” PDF version of the public account homepage from take to show him

  1. How is memory allocation allocated

What about heap, stack, reference counter, method area, local method area

  1. Soft reference, strong reference, virtual reference, weak reference those four references to explain their own

Speaking smoothly, I can’t remember the recovery time of the weak references. These four references are too strong in concept. I think I have already played a super role when I can remember these four references from a long time ago

  1. What about Java garbage collection

Free play, and C comparison, etc., talked about the disadvantages, here is the end of the virtual machine part

  1. How is study at ordinary times study?
  2. Starting with Java basics, how is sychronize implemented at the bottom?
  3. What kind of lock is synchronize?
  4. Synchronize Common scenarios?
  5. What kind of properties, variables can synchronize modify?
  6. Synchronize What happens if you lock a string?

I don’t know, I’m answering from a memory allocation point of view, but strings can have constant pools and heap areas and things like that. Later I searched for the question and found that the answer was generally in the right direction, but the question was actually very informative

  1. What are the synchronization mechanisms for threads?

This time at first I didn’t react in what to ask, the interview officer person guide me very well, and also asked me if I had studied the operating system, well but a bit earlier operation systematics, almost Waterloo, but also to understand the knowledge learn nginx, give the answer, here is very panic, thought for a long time, I am a little mess, the interviewer don’t call me with a smile

  1. What are thread states, and in what order?
  2. Thread and process relationship? If a process has multiple threads, what is the problem when a thread crashes?
  3. From thread synchronization to locks, how many locks do I know?

Five of them. A brief introduction

  1. Do you know about spin locks? explain
  2. Pessimistic lock optimistic lock how to understand say once?
  3. Let’s go to the computer network

Network structure several layers, each say

  1. What layer does HTTP belong to, what is the transport layer protocol, what kind of HTTP is used, what layer does the gateway belong to, what layer does the router belong to? Are you sure? Which layer does the switch belong to
  2. What is TCP/IP and how did it kill layer 7?

I answered a little fast here, I made a mistake at the beginning, I was reaping the conceptual stuff, didn’t read it before the interview, the interviewer asked me to answer it again, my blood pressure is soaring

  1. What’s the data link layer for? What’s the physical layer for?
  2. What about IP protocol? Which level does it belong to
  3. Type a web address into a browser and describe the process from the input to the rendering of the results to the page. DNS was asked during the answer
  4. It’s algorithmic. God forbid

The first one: Give a positive integer, check if it’s 2 to the NTH power, and he says the fastest way not to recurse? It has to be a way of doing things. What can you think of as a number operation, besides addition, subtraction, multiplication and division? This place talked a lot, too many calculations, but the feeling is not what the interviewer wants, I finally explained the binary shift, only to get his point, asked what else, he finally asked me why I did not mention the or, and how many binary numbers for me to calculate the result of the or

The second: To an array, the array with RGB three species, quantity and order complete disorder, and give an algorithm according to the r in the front, he wants g is in the middle, b all behind, calculated using the algorithm of mobile number, this place has been called me write algorithm to optimize the, it’s driving me crazy, I said I want to give up, He said you had a strong curiosity on your resume, so I had to think about it. I laughed and then I relaxed and continued thinking. It was psychological warfare

  1. The q&A session is over let me wait a minute and the second interviewer will be on the line for an hour and a half

The second plane

At the end of one side, I filled a cup of water and went to the bathroom. The second side came to me. The second side was also a little brother with soft voice and white skin, looking more elegant

  1. To introduce myself
  2. Ask me plan net, operating system, composition principle, data structure which learn best? He asked me to explain in detail what I was most familiar with, because I had read a lot about it during my internship

I talked about HTTPS encryption and decryption, symmetric encryption and asymmetric encryption, CA digital certificate and so on, explained in detail

  1. Can YOU secure your data using HTTPS?
  2. Which layer of the network model does THE HTTP protocol reside in
  3. What is the essential difference between TCP and UDP? This place digs more deeply into data reliability

I feel like I’m hitting my toes with a drill

  1. Practice with HTTP protocol to do things, HTTP status code to explain
  2. HTTP requests, get, POST, whatever else
  3. Is there a problem with using POST to get data? What’s the difference between GET and POST
  4. The difference between C and Java, essential difference

I talked about object orientation and process orientation, and he asked me to explain what object orientation was and then explain the two different ways of thinking in a popular way. (I answered a lot about this, but many of them were not what he wanted. He told me to calm down and finally gave an answer that he was somewhat satisfied with.)

  1. What are the characteristics of object orientation? When to use inheritance and when not to use inheritance? Have you ever come across this use? Why does inheritance break encapsulation?
  2. Has multithreading been used in real projects? For what?
  3. How to solve multi-thread security problem? How to solve the actual project, scenarios and solutions
  4. Multi-threaded collaboration, what else is there besides locks
  5. Explain the semaphore. What’s it for
  6. How do deadlocks occur
  7. What if a deadlock occurs?
  8. Banker algorithm
  9. Here we go. He’s here with the algorithm

The first one: there are a lot of cardboard boxes, each cardboard box inside a cardboard box, one of which has a coin, how to find the coin, write algorithm

Second: tree traversal method has what, write a binary tree front order traversal calculation method

Three governor’s sides

After the second interview, he said that he could not tell me the result. I thought it was cold, because after the first interview, the interviewer asked me to wait for the second interview. However, the HR contacted me for the third interview in less than an hour, which was about 5 PM the next day. The waiting time is very long, fortunately, I have a good attitude, do everything to listen to the fate.

Three interviews from five to six fifteen minutes, lasting 1 hour and 15 minutes, the interviewer is a handsome and handsome young brother, hair yellow hot dye very fashionable very long, very young, serious and resolute, speaking capable. Because I did not know how to press the end of the recording after 25 minutes of interview, I forgot many questions later and only recorded the questions I recalled in my mind in time

  1. Let me introduce myself
  2. Tell me one of the most challenging things about working on your own project
  3. Compare the advantages and disadvantages of mysql and mongodb
  4. Mysql uses join to connect to mongodb
  5. What is the difference between mongodb and mysql in the way of redundant fields
  6. Information has changed, name has changed how do you deal with these redundant fields

He spoke very fast, but said very clearly, with my thinking are fast up, every time follow me to answer the thing dig down

  1. Will alternate games in mongodb be used (for example)
  2. Pipeline operation mechanism is what, if you do mongDB execution engine, their own design a way to design this pipeline

I answered this question for a long time, because I didn’t understand pipeline at all, so I stuck to design.

  1. What problems do you think Docker can solve? Why use Docker for deployment? What are the benefits?
  2. How to implement file system mechanism in Docker?
  3. Inside docker root directory CD.. Can we get out of the sandbox and back to the host?

This place Waterloo, I guess to answer the quarantine mechanism, but I have forgotten the exact quarantine mechanism, the interviewer really wanted me to say more

  1. Asked me the level of front-end knowledge? React and jquery?
  2. Let’s go straight to the algorithm

The first: Finding the nearest parent node, gives two examples, almost leetcode medium difficulty

The second: open question, the cat catches the mouse, the cat is in the middle of the circle, the mouse is on the circumference of the circle, the speed is the same, ask the cat can catch the mouse, he is not satisfied with my answer to this question, I have explained the key points but can not use mathematics to explain

The content of the director is my relatively weak place, I understand the use but not very in-depth, asked me if I have learned “principle of compilation”, I did not learn. Before I asked him, he finally told me that he could not give me the answer. Finally, he needed to communicate with the other two interviewers to make a decision, and HR would contact him in two or three days. The director is mainly looking at ways of thinking about problems, like cat and mouse problems.

conclusion

The three interviewers met for a total of four hours and bled my soul dry, from start to finish. A particularly important experience is that it is normal to face the knowledge blind area, but do not give up immediately if you do not know each question. Think about it more, sometimes the interviewer will ask you, at least to explain your ideas clearly, but do not fool the interviewer with nonsense, to be reasonable and reasonable at least to justify yourself.

In the end, it was not passed. Although it was not passed, it was also a good experience. Byte interview experience was very good, efficient and not cold. We must be fully prepared, brave to try, bold to cast, I wish you all can have a good future!