Last wrote a get together face The Times, the public, the background some readers feedback said see of wanting more, hope I update the face of the other companies by as soon as possible, here to say sorry first, isn’t me too lazy, but the team just have a activity to catch online before the Spring Festival, so these days often work overtime, can only work to write off and on, If you look at the typesetting of this article some messy, but also hope forgive me!

background

Say the first personal situation, I graduated 17 years, begin by the end of last year, well is four and a half years of work experience, interview on this side of the guangzhou company mostly, have gathered era, byte, ali Lazada, tencent, netease company, finally got the opportunity and netease offer, in addition to gather time went well, I met with other companies for more than one time, and the final result is not very ideal, but I am satisfied with it. After all, compared with my previous job, this job-hopping is also a career leap.

During this process, I also learned a lot of experience. After the interview, I would record and review the questions I remembered, and review afterwards to make up for my shortcomings, which also made myself more and more handy in the subsequent interview performance. Therefore, I dare not say anything about other positions, but if you are the students with five years’ experience, I believe my experience will be helpful to you.

instructions

Here to share my interviews with several companies face the, I’m going to use bo + experience the combining ways to introduce and explain here, because the club for a lot of questions are related to the project, and have a few interview questions below, repeat, so I wrote the following real interview questions not so full, also do not recommend you to go back the answers to these questions, After all, everyone encounters different topics, what we need to do is to understand the general direction of the interview investigation, and then look at the shortcomings, as soon as possible to make up for their own knowledge blind area, only they are hard enough not afraid of steel temper (this is a little middle two, but I have no words)

Byte surface by

Byte is the company THAT I have interviewed the most, and I have met with them more than four times. To be honest, BYTE’s HR sister is very warm-hearted. Generally, she will inform you on wechat within two days after the interview.

In these several interviews, I was brushed twice in the end of the technology (vomit ah), and once in the HR interview, the range of knowledge asked was almost the same. It is not necessary to write all out, but to share with you some representative interviews, which is the interview topic for the back-end post of byte international e-commerce department

The interview questions

To introduce myself

Are you familiar with Redis? Why is it fast

There are several data structures. How are they stored underneath

Redis has several ways of persisting

How to ensure thread safety in multi-threaded situation?

Ever used volatile? How does it guarantee visibility, and how does it work

MySQL index structure, clustered index and non-clustered index difference

MySQL has several high availability solutions, which one are you using

Tell me about the most challenging project you have ever worked on

What parts of the project did you work on, what were the most challenging, and what optimizations did you make

What is the scheme adopted by seckill, how to do the sub-table, how to do when Redis hangs,

Why should we stop the operation? What can we do if we do not stop the operation

How do you keep coupons from being swiped more than once?

How to guarantee idempotent data in Redis (similar to distributed lock, have a key is ok)

Design:

1. If you were designing a high availability solution for mysql, what would your priorities be

2. How to design douyin comment system? How to add friend relationship? (Considering the performance of data reading, write diffusion can be adopted)

3, how to design a short chain address, to consider the problem of cross-machine room deployment

You said to hash algorithm to generate short chain, what problems will exist (hash conflict), how to solve? (Bloem filter can be used, but it is difficult to control and still hash conflicts)

Is there a better plan? (Increment sequence algorithm, each time a long chain is received, an ID is assigned, which is converted to base 62 and then spelled after the short field.)

The problem? (If the auto-increment ID scheme uses the Snowflake algorithm, there may be a problem of machine clock callback, resulting in the id duplication. Here, I finally understand why the guy said to consider the cross-room deployment problem.)

How to solve it? (Redis to do the self-increasing ID generator, high performance, but to consider the problem of persistence; Or modify the Snowflake algorithm to solve the clock callback problem by modifying workId)

Algorithm:

1. If you have an array of non-repeating elements, order them up and then down to find the largest value in the array (dichotomy, consider the boundary case with only one element and two elements).

2, linked list deep copy

3. Count the maximum number of online users and the number of users accurately to the second.

Soft power:

1. How do you evaluate yourself

2. What do you think about e-commerce? Why do you choose e-commerce

Is there anything you want to ask me

Summary: I attach great importance to algorithm and scene design, and I made a very detailed investigation of the e-commerce project I had done before, probably because I was assigned to the e-commerce department

Tencent’s surface via

I have two interview tencent, two are 2 face hang up, in addition to the two aspects of the second (free youdao is very tricky scene, I will write an article to share alone), other interview question is not difficult, to be honest I think a pretty well, the second plane was brush I also am a little wonder, forget it, don’t complain, you look at yourself.

The interview questions

A:

Tell me what you were responsible for doing this e-commerce project

Based on what dimension sub-table, what if you search for the product name,

Why not partition? What are the pros and cons of partitioning

What are the options for Rocket clustering?

If a, B, and C can write at the same time, but C hangs, can C still subscribe

Mysql high availability has several solutions, what are the characteristics of each

Redis distributed lock how do you use (redission), the principle know

Redis hot key? What can I do if a hot key causes high access traffic on a single machine?

If multiple Redis are distributed, what if a cache expires and the traffic is too heavy?

If 10 machines fail at the same time, how do you do it all at once

How is limiting done, using Ali Cloud sentinel, there are several strategies (QPS, time)

There are several traffic limiting algorithms, what are their advantages and disadvantages

2:

Describe your responsibilities and responsible modules for the project

Daily activity of the project, QPS, pressure measurement results

Is the project based on Http or RPC access? How is Dr Implemented

How do you do consistency with MQ

How do you prevent wool pulling and all that

The number of current team members, your position in the team, regardless of business experience, why do you think you were hired to be the technical leader of this project

What technologies and business directions are you currently working on

Career planning for the next two or three years

What do you know about GO, and for what purpose do you know about Go

Summary: Most of the questions are based on the project and the scene

Ali Lazada

There are only two rounds of Lazada recruitment technology. I am not bragging, but I have confirmed it with the internal promoter and the interviewer. At that time, I asked my friend to do the internal promotion before the interview began more than half a month later. Personal feeling ask is still a little difficult (but I think the answer is ok, was brushed after depressed for a while, big factory really not good to enter ah)

The interview questions

A:

Tell me about a project you’ve worked on

What were the highlights or problems solved

You said to introduce MQ to decouple the coupon interface. I understand that the coupon interface is relatively simple. Why do you need to decouple the interface so much trouble and asynchronism will affect the user experience?

(The coupon process is very long, and many coupons are received at one time, which has a lot of judgment logic and great access pressure. In order to reduce RT and access pressure, MQ is introduced to do asynchronous warehousing, and the user experience will not be affected)

Why should fen Biao stop serving?

What is the maximum QPS of your service, how many visits can your database support per machine, and how do you measure that? (A very troublesome problem)

Why don’t you talk about Java thread pools, how do they work, and when do tasks in queues get executed

How and why is your project thread pool configured

Spring Bean lifecycle

Why is Redis fast? You talked about supporting multiple data structures, why does this increase speed (easy to call native underlying data structures)

Are you still on the job? Do you have any other offers? When is the soonest you can start work

Do you have any questions for me?

2:

To introduce myself

Tell me about your latest project. What’s the business

What’s the mall business you’re talking about? Which part are you in charge of

Have you encountered online problems? How to solve them

You guys use Springboot, right? How do you call microservices

Have you seen Feign’s underlying principles

How do I change load balancing parameters

If you could design load balancing, what would you do

What are the reasons for the high CPU speed

Has hotkey been tested? How is it optimized

Let’s do an algorithm, two non-negative integers that I want to add, and I get a string output

Personal evaluation: Lazada asked more about the project, and attaches great importance to performance optimization, including parameter configuration, architecture design and so on. There is no big problem with the eight-part essay. In general, this interview is very able to investigate the experience.

Rule of thumb

The above is my interview of these companies about the topic, how to say it, not very difficult, NetEase asked about the same, not specifically listed, and are conventional questions, I will not list the answer, if you have questions to search the Internet, or add my wechat consultation.

From my interview so many rounds of the situation, the company recruitment interview focus on the scope of the applicant’s past projects and technical scenes, the eight-part essay words are not as comprehensive as the school recruitment, but each company will ask the focus of knowledge will be different.

In addition to the project scenario, Byte also values algorithms and the candidate’s thinking in system design;

Alibaba Lazada focuses on the architectural design of the project and the troubleshooting process of online failures

Tencent’s words ask more is the scene of thinking, such as what Redis a key page view of the relatively extreme situation, there is also soft power ask more

Here is my experience, but also to share my personal experience

1, the first condition: prepare the basic eight-part essay

There is no need to say more about the basic knowledge system, which will be asked in all interviews. Although the social recruitment is not so comprehensive, the basic Eight-part essay should be mastered as much as possible, including but not limited to:

  • Java basic language features (object-oriented, abstraction, inheritance, polymorphism, reflection, etc.)
  • Java collection (HashMap is mandatory, common procedures such as the number of lists, 1.7 and 1.8 expansion mechanism difference, why the thread is not safe, hash index calculation, and ConcurrentHashMap underlying structure, similar to the difference between HashTable)
  • Concurrency programming, needless to say, is also a basic question, after all, thread safety is all language development will encounter a difficult problem, but also the actual project development of a very important point (Synchronized upgrade lock process, and the difference between AQS, Volatile keyword principle and characteristics, how to ensure thread safety, Multithreaded implementation of producers and consumers and so on)
  • JVM (garbage collection algorithm, JVM tuning, CMS and G1 differences)

In addition to the Java language, basic computer network foundation is a must to pay attention to the field, be sure to master these pieces of content, such as

  • Computer network protocols and functions
  • Differences between TCP and UDP
  • Three-way handshake and four-way wave, and by the way, weird questions like why not two-way handshake
  • How to ensure the reliability of TCP, which mechanisms, and principles should be clear
  • HTTPS principles (three-way handshake, verification, encryption and decryption)
  • The entire process of entering a web address by the browser

Network to master it is almost a few pieces, then the operating system will also be necessary to prepare related, need not too complicated, just common interview question those who can, basically, as long as according to the above several preparation foundation especially this is about, of course, do not rule out some of the interviewer will ask some questions difficult and unpopular, I can only say four words,

Good luck!

2, commonly used middleware must be more prepared

Common middleware such as Redis, MySQL and MQ are basic requirements. We should not only know how to use them, but also have a certain understanding of their principles. More importantly, we should try our best to prepare solutions for abnormal scenarios of these middleware before the interview.

For example, Redis has a key access high, cache penetration occurs, Redis is down, how to ensure consistency with MySQL;

MySQL index failure how to troubleshoot, how to do SQL tuning;

MQ consumption exceptions, how to ensure high availability from producer to consumer, what to do when messages pile up, and so on;

These abnormal basic are often asked in the interview, a lot of big guys on the Internet have also shared the corresponding solutions, in my eyes, these knowledge points are eight essay, as long as adequate preparation in advance, take a middleware proficiency points basic no problem.

3. The items on your resume are the ones that require the most preparation

I can brag about the project, because I’ve been asked so many times, it’s almost a rote memory.

In my experience, the interviewer looks at the resume in several dimensions,

  • The overall architecture of the project, including how many services, how many nodes, what is the call chain
  • The most challenging module feature you’ve ever worked on
  • The business design of these functions includes what data tables are there, what middleware is used, and how to do data linkage with other services
  • What optimization did you make in the project? Is there any effect? For example, RT is reduced by 200ms, pressure measurement data is increased by 5 times and so on
  • What online problems have you encountered and how did you troubleshoot them
  • How do you think the QPS related indicators of the project can be optimized? Suppose there is 10 times more traffic coming, how do you think the design can support such a high volume of visits

Probably this time, everyone from specific interview questions I wrote above can also be a corresponding, basically asked what is contained in these dimensions, from global to a particular module of the project, some important data index, and scalability of the whole architecture, and exception handling and so on, these things if you don’t have to prepare in advance, I bet you can’t fool around with a battle-hardened interviewer.

In addition, many times in the project, there will be a scene exception investigation, such as what Redis failed to do; How to perform data rollback if the service invocation in front of the microservice invocation succeeds and the service invocation in the middle fails? A service is down how to handle and so on, these are the scenes similar anomalies often asked in the project, the reader, if have intention to interview in this regard may need to prepare more, as long as the actual business combined with the project emergency and preventive measures, is the emergence of these anomalies can effectively reduce the chance of.

Written (by the way, the last time together age face also involves the abnormal Settings in the content, then there is the reader comments hope I introduce what are the solution, a very simple request, but unfortunately, limited space and theme, I can’t here, was introduced in detail, according to these scenarios in the future plan I will organize to share in other articles, here to say sorry first)

To continue the subject of the project, in general, project this is the most worth to spend effort to prepare, but from my personal experience, social projects for interview review time proportion at least more than half, many teachers knowledge finally will implement the project actual usage scenarios, such as Lazada side of the interview, The interviewer is from the perspective of teachers at the beginning, asked a lot of Java thread pool, contains basic parameters and the running principle, but the final purpose is to investigate in my actual project is how to configure the parameters of the thread pool, and how to consider to refuse strategy, these are combined with the actual business is needed to design more considerate, there is no silver bullet, After all, it is impossible for a million day system and a thousand day system to have the same parameters.

So I recommend at the time of beautification project, combined with the optimization of the business volume to think, as far as possible, if you blow big size 10 times, so also want to consider good to support the current volume of technical solution, from parameter configuration to the server nodes need to thinking in advance, and best to thinking and dimension to match some of the important indexes such as QPS, RT, These are also things that interviewers are looking for. Without the support of the perfect technical scheme, the high concurrency blown out, the large volume is just the emperor’s new clothes.

Algorithms and system design questions may be key to your competitiveness

Algorithm this thing how to say, many people talk about the color of change, because of the high threshold of mastery, and need to lasting brush, but didn’t also way, for the sake of the company, the thing we really want to go to work, but also need not worry too, the common topic to brush a few more problem is just that I’ve met several data structures, algorithm problem have focused on nothing but Like what chain table, binary tree, array, other temporary didn’t come across, we put the structures related to popular algorithm of more brush is about the same, if I can in view of the company to better prepare to interview, the interview questions, it is not hard to find, also attracts and LeetCode on a lot of, the key is to persistent brush, don’t be a problem for three days off for 2 days this operation, Algorithms don’t accumulate without some time and perseverance.

And system design we also can gain more at ordinary times, like any common design seconds kill heat system, design, big flow, such as a list of basic is involves high concurrency large amount of data related to common topic can know about the design, in general, this kind of system design problem not very detailed, basically be to see your design ideas and contingency plans for abnormal scenario, It is difficult to be convincing in these two aspects temporarily, and it still needs the accumulation and thinking at ordinary times. When we are free, we can imagine abnormal scenes and discuss the feasibility with colleagues more often. After lunch, it is also an interesting way of communication.

Soft power is not difficult, but it also needs preparation

Soft power that is no big difficulty, everyone according to their own situation to answer is about, is generally end surface technology, the interviewer will be fastidious, purpose is to understand the processing power of your work and future plan, such as whether judge the role I will not do, in general, the soft power of the topic is not too sharp, Over the years, interviews have been asking questions like:

  • Where do you see yourself in the next three to five years
  • What are your strengths and weaknesses compared to your peers
  • What was the biggest challenge in your work, not just the technical side, and how did you coordinate it
  • If you came to us, what would you want from us

These questions have no fixed answer, vary from person to person, according to their own ideas to express can, but I still suggest that you can prepare before the interview under the words of this skill, nothing else, at least in the interview process can be fluent and clear expression, can prepare in advance point as far as possible do not go to temporary play that step.

Speaking of which I want to ridicule, technical interview is not something that can’t ask soft power, but in my opinion, it is a most auxiliary role, after all, nothing to answer the threshold, a lot of people can answer it, if not from technical issues, but ask a lot of this trifle things screening people, on the background of poor job seekers, I’m afraid not. (My humble opinion, do not spray if you do not like it)

6, good attitude

This is me the most simple advice to anyone, no matter what the situation, as far as possible, keep good state of mind, the environment is not good, many companies hiring standard actually is getting higher, more or less likely took pains to prepare you for a long time, but the interview process and the results are unsatisfactory, this is normal, after all is a giant, If it was that good, there wouldn’t be so many people looking for it.

And it was not a failure to decide the result, actually big opportunity always, a post didn’t pass the interview lock at most six months to a year’s time, after this time we can still go to the interview, and sometimes also don’t have to wait for so long, the department did not perhaps can interview other department of posts, as long as summing up experience, try many times, A bad result is better than nothing.

The last

Streaming voluminous wrote so many, with questions, combined with experience, and spent a week, I was to share the valuable surface through the, if the reader feel pretty well written, still hope can give me the three support, not three, lift a finger point is ok, I’m impressed, ha ha.

In a few months, it will be the peak job-hunting season. If you are also looking for opportunities and have several years of work experience, I think my article can give you some help. Here I sincerely wish all of you who want to change jobs, I hope you can get the ideal offer.

Author: MY Humble Xue, an Internet person who does not stick to technology, like to use easy to understand language to deconstruct the back-end technology knowledge points, want to see more wonderful articles can pay attention to my public number, wechat search [HUMBLE Xue] can pay attention to