Advantage for many no qualifications, interview companies is very difficult, this for me, too, from 2, thought is three point one line of life through life, until life changes, just let me have the new ideas and goals, so I this 2 Tony also struggle to get up, unexpectedly won the ali P6. Today, I share this experience mainly in the hope that it can inspire technical people who are also troubled by academic qualifications and have a reference value for their career and technical planning. Thank you!

A, interview ali P6 difficult where? (Interview difficult points)

(1) Difficulty lies in “mentality”

The first hurdle to overcome is actually your own state of mind. Because I was born in the second Ben, the base is relatively low, so the interview with Ali Ben is not very confident, let alone senior development post, so it is easier to have no foundation in mind. Therefore, before preparing for the interview, it took a long time to adjust the attitude of the matter, so it is difficult to “attitude” is not right, the attitude is not adjusted, the interview is almost impossible.

(2) The difficulty lies in “requirements”

The second is the requirement, the so-called requirement is actually the job requirements of Ali, that is, as a developer, how much technology stack do you master?

First of all, you have to have something on your resume, and second of all, you have to have something bright, which means you have a deep knowledge of a particular technology, so that it’s refreshing to the interviewer.

So, interview ali P6 post, need to master how much?

Java collection: HashMap and ConcurrentHashMap, usually best have read some source code, best know why each parameter is set to so large? What are the benefits?
JUC packages must be learned, even if the usual programming is not necessary, but also must be able to. Unsafe, volatile, sync, and other common lock-deadlocks and thread pool parameters. You also need to understand spin, blocking, deadlock, oom, CPU overload, and other basic operations. But that doesn’t mean you can’t do things like top, JPS, JStack, jmap. As well as possible derivative JMM models and MESI protocols.
JVM: garbage collection algorithm, garbage collector, JVM memory model, usage of each region, various OOM types, JVM tuning experience, class loading process, parent delegation, etc.
Spring has to take the time to look at the source code, usually asking about the bean life cycle, how to solve cycle dependencies, implementation of transaction principles, dynamic proxy principles, etc.
Dubbo also has to ask, design framework, load balancing.
What are the types of single-threaded models, AOF, RDB, rewrite, master-slave, cluster? Contains some common cache problems breakdown, penetration, avalanche, data consistency, and so on.
Mysql, transactions, locks, indexes, B + trees, master slave these are the things you need to know
Mq, I use RocketMQ, you have to know why use, repeated consumption, sequential messages, transaction messages, high availability, message loss, squeeze scenario, the whole process of message sending consumption, read the source code better, better blow
What about Netty, zero copy, BIO, NIO, AIO, architecture design? Used to see better
Algorithm, it is suggested that to brush, my luck is good, simple arithmetic, let I met some fast row, heap row, binary tree, list the reversal of cyclization, link points, jump the stairs and other conventional simple algorithm suggested brush, double needle, dp, recursive these still look for the feeling, big data limited memory scene, have time to try some middle may, Handwritten red black tree if you can, then I estimate the algorithm you steady.
Network, HTTP, TCP, HTTPS, UDP, layer 7 network protocol, etc., the best combination of their own understanding, back, you have to recite down.
There are also some distributed transaction implementation, architecture implementation, such as grabbing red envelopes, high concurrent orders and other conventional scene design, you design, how do you design? Find some more big cattle or check online, help you see what loopholes, what solutions? What are the best middleware in the industry?

Two, Ali interview questions (a total of 5)

Ali side:

Self-introduction, projects and technical areas
Talk about sync’s underlying implementation, lock optimization, versus Lock
Take a look at the details of JVM parameter tuning
Why? What are the benefits? Describe GC scenarios, how to analyze GC logs?
Redis data structure, usage scenarios, micro-blog scenarios how to design user relationships using Redis?
Thread pool parameter setting, why this setting, function? Seven parameters
How are Spring’s loop dependencies resolved? Why level 3 caching?
What is the underlying principle of priority queues?

Second face of Ali:

Let me introduce myself
Chat program
Combine your project to ask you how to design, put forward loopholes, how do you solve? How to improve, in case of failure? Is there a problem with adding a machine? What if I have to get it right?
How to design high concurrent single order inventory scenario
RocketMQ architecture design principles
Dubbo framework implementation principle
What have you read recently? How do you study?
Can you tell me how to use load balancing?

Three aspects of Ali:

This aspect mainly asks about the project, which gives you a strong sense of pressure
Combined with the project to ask, why so design? Let you optimize, how do you optimize, guide you to optimize in a reasonable and better way, database design and so on
What did you do in the company, what did the various systems line of business do, your performance, handwriting algorithm list inversion?

Ali four sides:

What are the main components of the JVM and what does it do?
What does the JVM runtime data area contain?
JVM garbage collection mechanism, when to trigger MinorGC, etc
JVM garbage collection algorithm:
JVM tuning tools?
Common JVM tuning parameters?
Stack difference?
What about the CMS garbage collector?
How do I determine whether an object can be reclaimed?
What are the new generation garbage collector and old generation garbage collector? What’s the difference?
Java class loading process?
Tell me everything you know about middleware (momentarily confused)

HR:

Why ali?
You never thought about Ali before?
What do you think has changed the most about yourself since graduation?
Sum up yourself in one sentence

What preparations have I made before the interview with Ali?

Java interviews are a cliche these days, and they are. ** Interview questions, interview guide, interview manual…… All kinds of Java interview questions one search a lot, can’t finish reading, also can’t see over, ** and each interview data also feel Nice, and then opened the collection of road.

Java developers should not be easy to be satisfied, now with a 20K job, the next step is thinking of taking 50K offer, or even annual salary million is very common programmers, not satisfied with the status quo, the body should have the ability to take its position, constantly improve skills, technology stack, are essential!

In fact, many people do not have a clear plan for themselves, and even do not know what route is suitable for them. In this way, you will be farther and farther away from the desired offer! Whenever you need to have a clear understanding of yourself, do you plan your learning route in advance?

If you’re thinking of moving on, stop and take a look. Can be more systematic, methodical review, preparation.

There are the following benefits:

Can review through a system, do not know where to look, how to start?
Set up a systematic review system where each knowledge point is independent and connected?
Review and summarize the major factories often test the pilot, from their own reality, to understand where the gap?

In addition to these, of course, there are some very beautiful learning materials, summed up very comprehensive, including 29 knowledge points, from the foundation to the advanced have! If you need the full version of this article, please click here to get it for free

Java Interview Core Knowledge Manual

When I saw this manual, I felt very conscience, including JVM, multithreading, Spring buckets, microservices, networks, message middleware, data structures, algorithms, distributed and so on:

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