Xiaoying technology phone:
1. The memory model of the linux process
It was such a question that came up, and I was directly confused. I can only say casually: code area, data area, heap area, stack area, and unused area. To ask again is to answer directly that I don't know.
2. Deduplication of 1 billion data
Hash segmentation, bitmap, sparse array. There are pros and cons to each implementation.
3. The realization principle of the underlying data structure of redis ZSet, how the jump table determines the level of inserted data
I didn't know this question at first. However, I don’t know if I’m dead. It’s randomly generated and determined by a weight probability. The larger the value, the lower the probability of generation.
4. How does HTTP implement the protocol? How to distinguish the head from the body?
What I'm talking about is the key-value distinction, and the header and body positions are different. I don't know what to ask specifically.
5. When TCP is connected, how many methods need to be implemented in Linux? What are the methods of association?
It can only be said that the client creates a socket, establishes a connection, the server creates a socket, binds bind, monitors listen, receives information accept, sends send and receives recv, and finally closes close.
Sadly, not satisfied, and I don't know what the interviewer wants.
6. Talk about microservices
I haven't done it, and it's clearly written on my resume. After the last Tencent interview, I also specially marked that I haven't used microservices. In the end, I still asked, indicating that the interviewer was here for a joke.
7. What has been done in service governance?
This is where I especially want to complain. I can only say that I know a little concept, service discovery and circuit breaking, as well as service registration and avalanche handling, etc. all belong to this category. Then he planned on me and asked the next one directly.
8. What are the statuses of HTTP? 302 403 404 502
This question is the only one worthy of joy. It is estimated that I am not satisfied with the previous ones. Ask a low-level question to try it out.
9. To create a large memory, is it a heap or a stack?
heap. The default size of the stack is only 2M. Some function variables are stored and released when they are used up. GC operations are mainly performed in the heap. Then I asked why it was designed like this, and I said that I never thought about why. I didn't even think about why it was named a stack.
I don’t know if you have noticed, but I didn’t ask any questions about Go during the whole process. I said, is the development of the back end all language-agnostic? I'm afraid I didn't have a fake interview.
I am convinced of the telephone interview:
This interviewer made me a little confused. I thought it was awesome at first, but when you went to find the answer yourself, you found out that the interviewer didn’t even know the question you asked, and the answer you said was the same. Incorrect. It can also be understood why the interviewer didn't give the answer on the spot, and insisted on letting you go back and search by yourself.
1. Judgment that the linked list has a ring, write pseudo code
Since it's a telephone interview, it's not about writing pseudocode, it's about pseudocode. However, can't a for loop be used for a linked list? I said that both for and while can loop through the linked list, I once thought I was an idiot.
2. GPM scheduling model
There is no other way to do this besides reciting. What I said, he kept saying um, sign recognition. Explanation, basic concept theory, everyone is on the same level.
3. The data structure used by the browser to move forward and backward
This, I started to be a little confused, I said that any data structure can be realized, that is the difference between trouble and simplicity. Then he talked about the stack and found that it didn't work. He suggested that two stacks could be used. Hmm, I agree with this approach.
4. In the three-way handshake of TCP, what information does the ack of the first handshake contain, and when will there be Time_Wait
This question made me completely subvert the interviewer. At the beginning, I didn't know what ack contained, I only knew that a serial number needed to be consumed. He said that it contained an ip address, but I didn't understand it. The first handshake to establish a connection is not ACK at all, but SYN. Secondly, ACK is the confirmation number returned by the server to the client, and there is no IP address or other information at all. The IP is only used at the beginning of the connection establishment. Although it is there throughout the process, I did not find that the IP was required during the handshake, and I did not find that the ACK would contain IP information. Time_Wait is only available when the connection is actively released.
5. What does the stack save, what about the heap? What is the direction of address growth? Why is it designed this way?
The stack space is opened and released by the compiler, mainly storing local variables and function parameters. I don't know the address direction of the stack. I reasoned. I have done a single-chip microcomputer before, and the pins are all processed from high to low. The heap is just the opposite of the stack. As for why it is designed this way, it is determined by the size of the end. I didn't know it at first, but I found out after reading the materials.
6. What is the stack size of Go? What is the maximum value?
I really haven’t noticed this. I always thought it was 2M. It turned out that it was not 32M as mentioned on the Internet, but 2K at the beginning. The stack will be split later to expand the size of the stack. In other words, the size of the stack will change. Yes, the stack size of the latest version changes from 2K-1G.
7. The queue realizes the optimal path
I don't know what to ask, it turned out to be a maze map, alas.
8. Two linked lists intersect like a zipper, and get these intersection points
I really don't know, I haven't found an answer yet. One intersection point can be known, but multiple intersection points like a zipper, I really don’t know.
9. After traversing the tree structure, how to release the memory information of the tree structure
This is the only interview question that I think has a level. The previous backward traversal has already been paved, and the release of the tree structure memory can only be released in the way of backward traversal.
10. How to check the network congestion of Linux and how long the process takes
This is mainly time spent. I said that the time cannot be determined, and we have no access to the server, so we can only assist.
11. For a TCP connection, what does the server do when it finds a packet loss?
I say retransmit. Then I asked whether to retransmit immediately or do some other processing before retransmitting? After the above questions, I am sure, this buddy must not know_
12. Greedy Algorithm
I don't believe that a few people can write it, if it is not a professional algorithm.
13. How does the queue ensure first-in first-out, and what about the stack?
Arrays, indexes, I don't know how to answer at all, and finally said that my answer was off topic. . . I want to say that I didn't even understand the purpose of the question.
14. How to distinguish linux permission control?
Don't know, different regions or? well.
Finally, ask him if you have any questions. I just asked a question. Do I have to answer all the questions you mentioned? Algorithms are a plus, he said. Then I looked back and, well, he was asking about bonus points.
Ping An interview:
The interviewer doesn’t ask many questions. He only asks details about the projects he has done. From the details, he knows whether you have participated or not, and whether you really know all aspects of the project. Then I asked a few Go inspection points, which are very simple, but you don't necessarily know the kind. The knowledge point is very simple. This is the process and question most in line with our normal people among my four interviews. The only thing that cares about your ability to deal with problems is whether your brain is flexible.
To sum up: If you can interview without a telephone interview, you can do a telephone interview, and if you can meet and communicate, meet and communicate. After all, in a hurry, we can still beat the interviewer.
We are used to stereotyped essays for interviews. To enter a large factory, you must recite those knowledge points that seem to be very advanced, but may not be used in a lifetime. Do we need to know why the stack address grows from high to low? During the interview with Go development, I didn't ask about Go. Today's headlines even directly stated that we are recruiting for Go positions, but no Go development experience is required. However, in order to find a seemingly high-end job, we wasted a lot of time to endorse, ignoring the things of our business itself, and we don't know if it's worth it. What is the point of writing a resume for such an interview? And those companies that insist on bringing paper resumes to the door for interviews, how stingy is this? At present, only Ping An's interviewer is normal, asking questions based on resumes instead of looking at the sky. They are all working part-timers, so why bother working part-timers. How should we deal with stereotyped essays in interviews? There are too many knowledge points to know how to start.