Ali side:
1: self-introduction
2: Face-to-face: Talk about what you have done in projects that have a deep impression or do you think you have done better?
Answer: I think I did a good job in Xx. I used XX requirements to implement XX functions, and the performance has increased by N times... Wait for a lot of crackling talk.
3: Face: You said that AOP is used, can you talk about its implementation principle?
Answer: It is realized by dynamic proxy, which is divided into JDK itself and CGLIB...
4: Noodle: Well, can you talk about their differences, advantages and disadvantages?
Answer: JDK is based on interface implementation, while CGLIB inherits the proxy class. . . (Just like this, I will keep asking, and if the conversation is almost done, I will start to ask some scattered questions)
5: JMM memory model, how is it divided? What are the contents stored separately? Is it thread safe?
6: Class loading mechanism, after talking about the parent delegation model, you will ask what violates the parent delegation model? Why?
7: Why do you need parent delegation What are the benefits?
8: How do you use multithreading? What are the benefits? The meaning of several core parameters of the thread pool?
9: The way of communication between threads?
10: The principle of HashMap: When it comes to thread insecurity, a natural extension ConcurrentHashMap, its realization principle?
11: How to design the sub-database and sub-table? Vertical split, horizontal split?
12: Business ID generation rules, what are the ways?
13: SQL tuning? What are the precautions for normal use of the database?
14: When an application starts slowly How to optimize?
15: Understanding of optimistic locking and pessimistic locking;
I can’t think of the others, probably the above. Finally, I briefly talked about the problems of the projects
I have done before. Tell me before the end and then I will change to a colleague to communicate with me. After hearing such a reply, I should be like this. Up.
One side summary
First confirm the degree of intention to Ali (if you are in a different place, you will even consider the degree of intention to work (Hangzhou)! Ali values this very much);
Secondly, the interviewer will generally communicate specific technologies for the projects you have done, and will pay more attention to whether the individual has a good grasp of the details of the project.
Mainly examine the technical basis and principles of java, such as the Spring framework and the three aspects of database and JVM, and will also discuss the implementation of distributed and thread pools, etc.
The key point is to investigate whether there are more researched technology and technical highlights [not necessarily every aspect is great, but there must be bright spots]
Ali two sides
1: Change the method to ask a lot of thread pool knowledge (mainly examine the corresponding parameters)
2: java memory model
3: the difference between lock and synchronized
4: the difference between B+ tree and B-tree
5: composite index
6: The difference between clustered index and non-clustered index?
7: What is the difference between the primary key and unique index of a database index?
8: Index failure conditions, when should the index be established
9: The difference between innDB and MyISAM?
10: Thread safety (blocking synchronization, non-blocking synchronization, no synchronization)
11: Talk about the Java class loading process?
12: Describe the principle and mechanism of JVM loading Class files?
13: What is GC? Why is there GC?
14: Briefly describe the Java garbage collection mechanism.
15: How to judge whether an object is alive? (Or how to determine the GC object)
16: What is the basic principle of the garbage collector? Can the garbage collector reclaim memory immediately? Is there any way to proactively notify the virtual machine for garbage collection?
17: Why are the stop() and suspend() methods not recommended?
18: What is the difference between sleep() and wait()?
19: What are the similarities and differences between synchronous and asynchronous, and under what circumstances should they be used?
20: Briefly describe
the similarities and differences between synchronized and java.util.concurrent.locks.Lock?
21: Please tell me the thread synchronization method you know.
22: What is a thread starved to death, and what is a livelock?
23: What is ThreadLocal?
Two-sided summary
In-depth understanding of technical strength, understanding of your knowledge, and your ability to solve problems and the ability to use technology flexibly according to the project. Through this process, you can also examine teamwork ability, learning initiative and innovation, and you can choose 2-3 Do a careful technical review and your own unique understanding of the typical projects you have passed [this will be your bonus item];
Ali three sides
1: Regarding the continuation hierarchy of Java exceptions, describe the continuation relationship of exceptions;
2: How do java threads start? What are the ways to lock in java and how to write it?
3: Understanding of optimistic and pessimistic locking;
4: How the heap is managed in JVM, JVM's memory recovery mechanism, introduce
5: the difference between redis cache and memcached cache, and their respective advantages and disadvantages
6: microservice architecture: The difference between dubbo and springcloud, and their corresponding usage scenarios.
7: How to load balance the thread pool
8: How to design single sign-on, the principle of single sign-on
9: The realization principle of synchronized? Can Volatile guarantee atomicity? why?
10: Tell me about GC?
11: TCP three-way handshake, why three-way handshake?
12: MySQL deadlock, how to solve it, if the execution order is not required, how to solve the deadlock
13: What do you think of Alibaba?
14: What do you think of 996?
15: Talk about your strengths and weaknesses
Three-sided summary
Their final executive re-examination will involve related technical issues, most of which are macro-controls of your overall values (such as self-motivated, responsible, mentality, work passion, etc.)
HR confirmation face
Basically, from the general direction, understand your mentality, ability to withstand stress, your role at work, general plans for the future, and your intention to Ali.
[Technical basics and problems, just read the book and prepare, it doesn’t matter if you don’t understand it, you can’t understand it directly; check the details of the project more, talk about your own technical highlights according to the project, can express it clearly, and you can guide The interviewer will ask you technical questions that you are good at, so you can play to your heart’s content.]
Talent characteristics that Ali prefers: passion for technology, strong technical foundation strength; initiative, good at teamwork, and good at summarizing and thinking ;
Pinduoduo
1. Give a function that returns 0 and 1, and the probabilities are p and 1-p. Please implement a function so that the probability of returning 01 is the same.
2. 1 billion URLs, each URL is less than 56B in size, requires deduplication, and 4G memory.
3. Convert a bst into a doubly linked list.
4. The difference between http and https, https is an additional process when requesting, and how does https guarantee data security.
5. IP address subnet division.
6. The difference between POST and GET.
7. The difference between hard link and soft link.
8. DNS resolution process.
9. The usage of kill, the reason why a certain process cannot be killed (enter the kernel mode, ignore the kill signal).
10. Commands used by linux.
11. System management commands (such as viewing memory usage and network conditions).
12. Use of pipelines.
13. The use of grep must be mastered, and every time you will ask to find it in the file.
14. Shell script.
15. The find command.
16. Use of awk.
Pinduoduo two sides
1. Some instructions under Linux, (process id), (process id), (process id),? (the status when the previous command exited), how to check the process, sort by memory size, CPU usage, etc. (Uppercase M and uppercase P).
2. The get and post methods of http.
3. Introduce what you know about epoll.
4. Knowledge of database sql.
5. The problems encountered in the project, how did you solve them, etc.?
6. Write a full array by hand.
7. B tree and B+ tree.
8. Introduce Hash and how to resolve conflicts.
9. The advantages and disadvantages of the communication between processes and the shared memory method.
Pinduoduo three sides
1. Tell me about some technical blogs and books you usually read.
2. Some instructions under linux.
3. What is the most uncomfortable thing at work?
4. Talk about your strengths and weaknesses.
5. Have you thought about starting a company in the past?
6. Write a strcpy function.
7. Tell me about your own character.
8. Give you a system (the interviewer seems to be from the unmanned vehicle department). The back-end logic has been implemented, but the front-end loading is very slow. How to detect it.
9. You may have to learn a lot of new technologies in the future, what do you think.
10. Difficulties encountered in the project (think well in advance and state the implementation or optimization method clearly).
11. The magnitude of the system, pv, uv, etc.
12. Solutions for high concurrency (distributed).
13. What are the main tasks in the project?
14. Load balancing of nginx.
15. The consistency of the distributed cache, how to expand the server (hash ring).
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