Top all major platforms, 22 versions of interview core knowledge analysis notes, strong on the list

A programmer roast that his energy was full , Tweet to vent ： I've worked on headlines 3 years , Unexpectedly, Ali was brushed down on one side ？ With what

Ali side

1、 Thread pool （ Specific parameters , Refusal strategy , The mechanism of reducing threads , The specific implementation class and the corresponding blocking queue , What are the characteristics of blocking queues , Why use this blocking queue , The principle of thread reuse ） 2、JVM（ Criteria for judging whether the object is recyclable , How to judge , Recovery algorithm , Categories and characteristics of garbage collectors , Guarantee mechanism ） 3、JAVA Memory model 4、 Communication between threads , adopt volatile,synchronized,Lock The implementation classes of , Combined with the memory model . 5、MyBatis、spring、springboot relevant （ Interview questions are more common ） 6、Linux Common commands 7、redis The data structures , Talked about it. skiplist、ziplist、sds etc. , Combined with the use scenario

To sum up ：

The interview time 35 About minutes . Social recruitment side （ Life and death ） The first point easy to hang , It's just the general explanation of the initial project , No highlights . The technical difficulties and technical sticking points in the project cannot be expressed , It's easy to give the interviewer a kind of “ This man can't ” The feeling of . As for the basic knowledge, we still have to think more about it at ordinary times ？ How to achieve ？ So realize ？ In short, explain an excellent project , Half of the interview passed .

What to pay attention to

1. One or two pages of resume is the best , Write the project experience 2-3 It's about one , Be sure to write the starting time of the most bright project work experience clearly , In addition, the major companies have their own back tone , Don't merge or omit short work experience , Maybe it's not just the interview that's affecting , But after that, you may not be able to enter this company's blog, and there are no good articles ,github Don't write in your resume if you don't have a good project

2. For the interviewer's questions , Think clearly and then answer , If you think it will take a long time , You can tell the interviewer that I think about 、 I'll sort out my thoughts and say no directly when I encounter problems that won't , Don't pretend to understand

3. Encounter a relatively certain problem , Be confident , Sometimes the interviewer may deliberately look at you with suspicion During the interview Pay attention to speaking speed and enunciation , After I was an interviewer , I found that many people speak very fast , Or can't pronounce clearly , Leading to the original question will also make the interviewer feel that you didn't answer the point （ Especially on the phone ） You can be confident during the interview, but don't argue with the interviewer. Don't ask the interview result directly after the interview

4. Keep confident and not arrogant in the interview , Once asked a candidate to say yes hashmap It's as clear as a finger , It turns out that hashmap There is no need to recalculate hash I'm so confused . For many people , There's always a way for an interviewer to ask you down , After every interview Summarize what you didn't answer well , What are the blind spots of knowledge , Get rid of it .

5. When asked why they want to change jobs , We should start from the perspective of self-development , Make complaints about the company . in addition , In the process of applying for a job, I have met a few interviewers who are not qualified , For example, there is a disdainful tone when I come up , I started without saying two sentences diss Your project , It's a very bad experience . So please also invite the interviewers or the students who will be the interviewers in the future , Be able to maintain basic courtesy and respect during the interview process , As Ali used to say ： When you interview someone , Others are interviewing you, too .

6. The most important point , Don't start to doubt yourself just because you have failed in several interviews , Always remember , The result of the interview = power + luck . Sometimes what you're good at may not be the interviewer at all , So he can't spend a lot of time asking what he doesn't understand ; Sometimes when he asks you, you will , But maybe it's because of the way they ask questions 、 Tone and so on , The answer is not smooth .

Next, technology related investigations .

in general , Technology related investigations are mainly divided into two parts , One is the foundation , The second is experience .

• The foundation includes java Basics 、 database 、 Middleware etc. , From daily accumulation and preparation before interview .

• Experience includes previous projects 、 Problem solved 、 And some scenes （ For example, how to ensure the availability of your project if the traffic is ten times larger ）.

Let's talk about our experience , And reference documents . It is mainly a collection of high-frequency interviews organized by senior interviewers of large factories +Java Special roadmap for advanced learning , From the foundation → Threads →JVM→ Algorithm → database → Microservices → Interview experience and other interview questions of the whole technology stack , Xiaobian shares it for free , If you can finish it , It will be of great help to our big factory for interview, job hopping, salary increase and promotion ！

Because there are too many documents , The following will be edited without affecting everyone's reading , Try to show more to everyone , Friends who are interested in learning , Click here for , Get the full documentation for free download .

Multithreading concurrent programming ：

• The construction parameters of thread pool and their meanings , How to determine the number of threads in the thread pool

• How to implement the timed thread pool ？

• synchronized,volatile keyword

• Atomicity , Visibility and order

• Reenterable lock ReentrantLoc

• ThreadLocal Implementation principle of

• AQS Underlying implementation , And ReentrantLock The relationship between

JVM Knowledge point ：

• Memory partition

• OOM Introduce

• Object allocation and recycling

• CMS and G1 Garbage collector

• Accessibility analysis of objects

• Class loading mechanism

• JVM Tuning parameters

• Full GC,Minor GC

• Object on the stack （JIT compiler ）

MySQL Knowledge point ：

• MySQL Isolation level

• Consistency view

• Log module ：undo log,redo log and binglog

• Index structure , Back to the table , Leftmost prefix principle

• Clearance lock , Fantasy reading ,MVCC

• SQL Optimize the actual battle

Java Basics ：

• NIO Implementation principle of

• HashMap,HashSet,LinkedHashMap as well as ConcurrentHashMap

• hashcode And equals Differences in methods

• RuntimeException Exception Error

• Use of annotations

• Basic data type

• Five common networks IO Model

Spring&MyBatis：

• Spring IOC and AOP Principle

• SpringBoot Source code interpretation , Starting mode , Configuration sequence, etc

• SpringMVC and Spring The relationship between father and son

• Spring The transaction implementation of

• How to customize the implementation SpringBoot Medium starter

• MyBatis in # and  $ The difference between symbols

Network protocol ：

• TCP And UDP difference

• TCP How to guarantee reliability

• TCP network

Network packet fragmentation and reorganization

• Three handshakes and four waves , State transition

• SSL The encryption algorithm used in handshake protocol , It is the disadvantage of asymmetric encryption

• XSS and CSRF Introduce

Redis&Kafka：

• redis Implement distributed locks

• redis Data structure type

• redis zset Implement delay queue

• How to maintain the jump meter

• redis Threading model

• redis Data expiration method

• redis Persistence mode

• Cache avalanche , Cache penetration , Cache breakdown

• Kafka The theme , The relationship between partition and log file

• Kafka Log compression and deletion

• Basic characteristics of message queue

Algorithm title ：

• Find most elements （ Meituan ）

• The longest common string （ Meituan ）

• The singleton pattern （ Meituan ）

• Quick sort （ Ali ）

• Find the penultimate... In the linked list N Nodes （ headlines ）

• Merge k An ordered list （ Well quickly ）

• Reservoir （ Well quickly ）

• Custom implementation parseDouble Method （ Well quickly ）

• a+b+c=0 （ headlines ）

• Binary tree preorder traversal （ Well quickly ）

• The binary tree is traversed in the previous order and transformed into a tree with only right nodes （ Ape counseling ）

• Traverse the binary tree according to the zigzag （ headlines ）

• Keep the repeating elements in the ordered linked list , And keep it only once （ Ali , This is very interesting , Interested students can realize ） Given an ordered linked list , Keep the repeated elements in the linked list , And keep it only once , If a linked list is given 1->1->1->2->3->3->4.

The result is 1->3. Please write an efficient algorithm

• Use three threads to print A,B,C, Press ABC CBA ABC CBA … Print in the same order ( Ali ) ok , For those who are prepared , These algorithms are not too difficult . I will share my algorithm learning rhythm that I have hidden for many years , Help you prepare for the interview ！

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Finally, I hope everyone can pass the information in the article , Get what you love offer, Receive a salary that satisfies you ！！！