Last year's Golden September and Silver October, I joined the trend of promotion and salary increase like most of my peers. I started preparations as early as 2 months ago. I felt that I had no technical problems at all, so I was in the The company fished for 2 hours, and went home for 2 hours to read. I read thousands of interview questions back and forth, and Leetcode also read more than 100 questions!
To be honest, I was not nervous at all when I went to interview with Tencent, and even a little happy. After all, I am about to realize my dream of being a big factory, and I have even chosen a rental house!
There were no problems in the first two interviews. On the third interview, I went to the interview with confidence as usual. In the past two days, I have been imagining how to introduce myself on the first day of work. Unfortunately, I was careless and didn’t flash. The interviewer asked me a practical question about high difficulty and high concurrent system design:
How to deal with counters with massive data?
Me: "??? Abba aba aba aba"
Interviewer: "Okay, I have no more questions, and if I have questions, don't come to me"
The interview is over.
After waiting for a month, I didn't wait for the fourth round of notice, and I didn't go to interview other Internet companies. After all, I felt that I was better than myself at the time. Now this company continues to work for a few months (<font color=gray>but because there are many interviews and leave, the company has also seen it, and has been suppressing me, which is quite tormented</font>), until this year's gold medal Three silver and four rushed to Tencent again, vowing to beat the interviewer!
So I found my senior who was beyond my reach, and asked him how he learned high-concurrency system design in the first place?
Senior: "Now is the era of paying for knowledge, report to the training institution!"
Me: "No money!"
Senior: "Just kidding, you just take this information and learn it. If you still can't learn it after reading this, I suggest you become a Didi driver!"
Me: "Is it really that powerful?"
Senior: "Don't believe me? Then I withdraw it!"
Me: "You withdraw it, I have downloaded it all, don't be afraid!"
Before learning this, I took annual leave, went on a trip to relax, relieve my mood, and adjust my state well, prepare for gold, silver, and gold, so that there will be no more mistakes!
After I came back from the trip, I quickly got into the mood (to be honest, it’s really comfortable to relax and relax, everyone must go if you have the opportunity), and I took a closer look at the author’s writing style, which is more biased towards blog posts. Relatively speaking, the sense of distance is relatively small. This is a big shot.
When explaining the knowledge points, it is also from the shallower to the deeper, step by step, so that we can understand it well, and there are actual combats to help everyone consolidate it, and you can calmly face it under the difficulties of the interviewer!
Let me introduce how powerful this learning material is!
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Step ①: Basic
First of all, we need to understand some knowledge points:
- High concurrent system: what is its general design method
- Architecture layering: why do we have to do this?
- System design goal (1): How to improve system performance?
- System design goal (2): How to achieve high availability of the system?
- System design goal (3): How to make the system easy to expand?
Step ②: Database
In the first step, I have taken you to understand the basics of high-concurrency system design from a macro perspective. You already know that the purpose of our system design is to achieve better performance, higher availability, and stronger system expansion capability.
Then at this step, we officially enter the evolution chapter. I will start from the local part and take you to understand some of the methods that will be used to achieve these goals one by one. These methods will specifically solve the problems that arise in the design of high-concurrency systems.
- Pooling technology: how to reduce the performance loss of frequently creating database connections?
- Database optimization plan (1): When query requests increase, how to separate the master from the slave?
- Database optimization plan (2): When the amount of written data increases, how to implement sub-database and sub-table?
- Issuer: How to ensure the global uniqueness of the ID after sub-database sub-table?
- NoSQL: How do databases and NoSQL complement each other in high-concurrency scenarios?
Step ③: Cache
Through the study of the previous database chapters, you have learned about the evolution process of the database layer and the considerations in database table design under high concurrency and large traffic.
Then I will take you to master the design ideas and concepts of cache from the three aspects of cache definition, cache classification, and cache advantages and disadvantages, and take you to master the correct posture of using cache in a targeted manner so that you can do better in actual work Use the cache effectively to improve the performance of the overall system.
- Cache: After the database becomes the bottleneck, how to speed up the query of dynamic data?
- Cache usage posture (1): How to choose the cache read and write strategy?
- Cache usage posture (2): How to achieve high availability of cache?
- Cache usage posture (3): What should I do if the cache penetrates?
- CDN: How to speed up static resources?
Stpe ④: message queue
Within 1 second, 10,000 database connections reached at the same time, and the system's database was on the verge of collapse. It was imminent to find a solution that could handle such high concurrency of write requests. At this point you think of message queues.
Here I will take you to learn how to use message queues to solve the problems in the seckill scenario from the following questions:
- Message Queue: How to handle tens of thousands of order requests per second during seckill?
- Message delivery: how to ensure that the message is only consumed once?
- Message Queuing: How to reduce the latency of messages in a message queuing system?
Step ⑤: Distributed service
Through the content of the previous chapters, you have optimized the performance, availability and scalability of your vertical e-commerce system from the perspective of database, cache and message queue.
But there is a question that has been lingering in your mind: what prompted us to split the monolithic architecture into a microservice architecture? Does it mean that when the overall QPS of the system reaches 10,000 or 20,000, it must be split into microservices?
I will explain from the following points, why do we use distributed services? What is so good about it and how is it achieved?
- System architecture: Does a system with 10,000 requests per second need to be split into services?
- Microservice architecture: How to transform the system architecture after microservice?
- RPC framework: How to implement millisecond-level service calls under 100,000 QPS?
- Registry: How is a distributed system addressed?
- Distributed Trace: How to troubleshoot slow requests across dozens of distributed components?
- Load balancing: How to improve the horizontal expansion capability of the system?
- API Gateway: How to do the facade of the system?
- Multi-computer room deployment: How to do cross-regional distributed systems?
- Service Mesh: How to shield the service governance details of the service system?
Step ⑥: Maintenance
In order to quickly discover and locate problems in the business system, it is necessary to build a complete server-side monitoring system. As the saying goes, "There are tens of thousands of roads, monitoring is the first, and monitoring is not in place, and the leaders are crying." However, during the build process, your team got stuck again:
- First of all, how to choose the indicators for monitoring?
- What methods and approaches can be used to collect these indicators?
- How to process and display the indicators after they are collected?
These problems are interlocking and related to the stability and availability of the system. After completing these, I will take you to solve these problems and build a server-side monitoring system.
- Adding eyes to the system: How to monitor the server?
- Application performance management: How should the user experience be monitored?
- Stress testing: How to design a full-link stress testing platform?
- Configuration management: how to manage thousands of configuration items?
- Downgrade fuse: How to shield the impact of non-core system failures?
- Flow Control: How do we manipulate traffic in a high-concurrency system?
Step ⑦: actual combat
Earlier, from the perspectives of database, cache, message queue, and distributed service, I showed you how to ensure high performance, high availability, and high scalability of the system in the face of high concurrency. Although there are a lot of examples to help you understand theoretical knowledge, there is not a complete example to help you string together the knowledge.
Therefore, in order to put the knowledge we mentioned to the ground, in the actual combat chapter, I will take Weibo as the background and use two complete cases to take you from a practical point of view to deal with the impact of high concurrency and large traffic. I hope to give you a more specific The perceptual knowledge will provide you with some ideas when implementing similar systems.
- Counting system design (1): How to deal with counters with massive data?
- Counting system design (2): How to design a non-counting system at 500,000 QPS?
- Information flow design (1): How to implement the push mode of the general information flow system?
- Information flow design (2): How to implement the pull mode of the general information flow system?
Interview experience sharing
1. What is the core of the research and development interview?
2. Do you need to brush the questions before the exam?
3. What are the interview minefields in the interview?
1. What is the core of the research and development interview?
The core of the R&D interview investigation: In fact, to be honest, the core ability examined in the R&D interview is... the ability to code!
Coding ability is the foundation of computer science. Whether you can write clear, concise and logical code within a limited time can not only check whether the candidate has solid basic skills, but also allow the interviewer to have a basic judgment on whether the candidate is qualified for the corresponding job in the future.
After two interviews, I found that some candidates had a great time chatting about the project at the beginning, and answered some detailed questions quite well, but once they got to the level of handwritten code, there are many people who can’t even write binary search exist.
I usually write very little code, and an experienced interviewer can tell at a glance whether I have prepared before the interview. So here are three suggestions for you:
1. Enhance basic skills and increase the amount of code
Look at the excellent source code, carefully analyze how others implement a function concisely and clearly from the aspects of efficiency and logic, which is of great help to improve your basic code ability.
2. Do more questions before the interview, it is very important to keep the hand feel
Do more practice before the interview, which can not only speed up the answering speed, but also allow yourself to develop a more standardized answering habit.
3. Review the written test answers and think about better solutions
Finally, many interviewers like to review the written test questions during the interview, and discuss with candidates about better solutions to the questions, so as to examine whether the candidates have the ability to think actively.
2. Do you need to brush the questions before the exam?
But I hope to learn by analogy
During the interview process, there are often students who are very proud to confess: "I didn't brush the questions."
And here I want to express the attitude of the majority of interviewers: we are not opposed to brushing the questions, and even hope that the students can use them flexibly and understand by analogy after doing a lot of questions.
Doing a lot of questions can not only improve students' problem-solving speed in a short period of time, but also help you expand your thinking about answering questions to a certain extent.
Of course, if it is found that the students are brushing the questions, the interviewer will also change the question and check from the side whether the students memorized the answers by rote. As the interviewer of the spring recruitment and your potential future colleagues, we hope that the students can be flexible.
Therefore, it is time to prepare, it is time to brush up questions, and cramming for the time being at least reflects whether you attach importance to the interview? When your questions reach a certain level, you will find that your abilities have improved from quantitative to qualitative.
3. What are the interview minefields in the interview?
1. Being honest and trustworthy is the first priority of being a person, and it is also the bottom line for large factories to employ people.
Everyone should know that even in a video interview, the interviewer can see the candidate's behavior! Promise me, don't do things like "check the answers on the ipad while taking the exam"! As an examiner, it was embarrassing for me to see it on the other side of the camera...
2. Don’t dig yourself a hole
You are responsible for the resume you write yourself. Because during the interview, the interviewer usually takes your resume and asks about various details in it. Technical details, work experience, project status, etc. You have to be fully prepared for the hidden topics behind every word you write.
3. Resume should be recognizable
Usually a position may receive more resumes. How can you make your resume stand out from many opponents at this time and get an interview invitation? To have "recognition", the best effect is that the interviewer feels that after reading this resume, he really wants to meet this person.
4. Fine-tune your resume for different companies
Sometimes it is necessary to fine-tune your resume to the business of the interviewing company. For example, the other party is a mobile medical company. And if you happen to have done a similar project, you can rank the project introduction of this part to the first place. And the description of mobile medical experience will be emphasized. In order to achieve a better matching effect with the position.
end
No matter what technology is hot or not, learning is uninterrupted. It is the kingly way to sharpen technology while young. Otherwise, you will not be able to eat much if you want to be young in this career of programmers. Year. However, wanting to improve is one thing, and how to improve effectively is another. I have been working for nearly ten years, and I have also supervised many interns and fresh graduates. Many young people are really hardworking in their studies, working overtime and working hard, but they are almost too late, and the methods are still wrong.
What is the method? The method is to follow the big guys around you, ask more questions and learn more. If you don’t have a big guy around you, you can also join our learning resource exchange group. Friends from all over the country can chat and learn together to learn more about the industry, trends and trends. towards.
PS: Due to space reasons, the entire content of the information cannot be displayed here, only a part of the screenshots can be displayed.
If you need the full version, veterans can help Sanlian to support it. Click the portal below to get started~