Alibaba Java looks good at you from all sides? Now the interview is so difficult, it's not the era of memorizing questions

Recently, a friend told me that interviews are too difficult now, and it’s no longer the time to memorize a few interview questions and get an offer. Recently, my friend interviewed Ali for a job change, and then I exchanged some of the interview questions he encountered, and then I sorted it out, and then shared it with friends in need. By the way, I also checked and filled out the vacancies, and I was still sorting out A back-end study route notes are available at the end of the article!

Ali technical side

• Start by introducing yourself;
• The realization principle of HashMap, what is hash collision, and how to solve hash collision?
• The principle of ConcurrentHashMap and the difference with HashTable?
• The difference between HashSet and TreeSet and the underlying implementation principle
• The key-value is stored in the HashMap, and the value is repeated but all of the Comparable type can be compared; how to sort this collection according to the value, and introduce the implementation method
• What is the difference between the ReentrantLock and synchronized keywords?
• What does synchronized modify static method specifically say?
• Troubleshooting methods for cpu and memory exceptions during work; detailed analysis process and positioning solutions

Ali technology two sides

• JVM class loading mechanism;
• JVM memory model, what is the stack space, under what circumstances the stack memory will overflow, etc.;
• JVM garbage collection mechanism;
• The principle and optimization of a jvm;
• SQL optimization;
• Principles of SpringIOC and AOP (ask if you have any experience in source code reading)
• The principle of the framework used now, such as using dubbo, will ask about the principle of dubbo, and how h5 calls dubbo, etc.;
• Next is the project, the problem in the project is relatively simple;
• Then there are various basics, jvm memory model, nio, bio, aio, high concurrency, sychronized and volltail, HashMap, data structure and expansion;
• There are also some scene problems, how to design the system in the case of large concurrency/massive number. Take two points from it to ask, one is system decoupling, the other is sub-database and sub-table;
• The last one is the coding question. In the case where the key in the HashMap is a custom object, sort

One side and two sides JVM ask more about how to distribute the online version, redis commands, data structure, internal database lock mechanism, online problem solving, SQL optimization, etc.;

Three aspects of Ali technology

• The method implemented by executor service, the parameters that can be set;
• An algorithm problem is presented to find the nth node from the bottom in the linked list;
• I also asked the difference between thread and runable;
• What is a clustered index;
• Redis asked for a solution to a practical problem. If a value of redis is particularly large, what solution is there;
• Redis memory elimination mechanism;
• The default isolation level of mysql;
• paxos protocol
• Deployment across computer rooms, problems encountered and solutions, 9999 rate throughout the year
• In the DB architecture of MMM, the master is never fully synchronized, and the master is down. What impact will the unsynchronized content cause and how to recover
• What is the difference between nginx and tomcat? Can the two roles be interchanged? That is: tomcat as a reverse proxy, ng as a service container. Explain the reason.

Four aspects of Ali technology:

• Talk about what the project is mainly responsible for, what is the structure of the project in charge, what is responsible for it, etc.; I am more concerned about whether you understand financial knowledge and whether you have experience in financial project development;
• Hand drawn architecture diagram, mainly asking questions about middleware

to sum up

The question is very deep and too difficult. It’s no longer the time when you can get an offer by memorizing a few interview questions. But don’t give up. As the demand for recruitment becomes higher, you must continue to improve your learning. I saw a lot of feelings saying that the interview was too difficult, the interview was a rocket, and the job was screwed. That's right, that's it, but you have to improve, either leave the line or keep going. I have stayed in an industry for a long time. I really need a lot of courage to jump out. Everyone has a lot of things to bear!

For those who want to advance or have no direction, we will provide a core knowledge point of Java back-end interview. It can also be said to be an improvement direction. Friends in need can click here to get the information for free!

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