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Even liver three all night, jvm77 high frequency interview questions detailed analysis, this?

2020-11-06 01:39:17 Procedural ape space

Preface

After the painful spring and autumn moves , I've also accumulated some facial scriptures , I hope it can help you . Due to the word limit, those who need answers can pay attention to GZH【 Programmer space 】 Get the full version free of charge PDF

other

  1. What 什 Is idempotent ? What 什 In this case, we need to consider idempotent ? How do you solve the idempotent problem ?

Java

  1. Multiple threads read and write at the same time , Number of read threads 量 Far away ⼤ Larger than the writing thread , How do you think it should be solved Concurrent problems ? You'll choose gash 什 What kind of lock ?

  2. JAVA Of AQS Yes No 了 Explain , It is ⼲ What do you do? ?

  3. except 了synchronized Besides keywords , How do you ensure thread safety ?

  4. What 什 When do you need to add volatile keyword ? Does it guarantee thread safety ?

  5. If all threads in the thread pool are busy , Submit ⼀ A new mission , Will send ⽣ What's the matter 什 Well ? queue 列 All stuffed 了 after , Still busy , Submit again and send ⽣ What's the matter 什 Well ?

  6. Tomcat Your own parameters ⼀ How do you usually adjust ?

  7. synchronized What's locked in by keywords 什 Modong ⻄ In the west ? How is it represented in bytecode ? , What is the representation of the object in existence 什 Well ?

  8. wait/notify/notifyAll⽅ The method needs not 不 Need to be included in synchronized In block ? Why is this 什 Well ?

  9. ExecutorService you ⼀ How do you usually ⽤ With ? Is each service discharge ⼀ One is still ⼀ One item ⽬ Objective ⾥ in 里⾯ Put ⼀ One ? What do you have 什 What's the benefit ? Spring

  10. Do you have ⽤ Used to Spring Of AOP? yes ⽤ be used for ⼲ What do you do? ? ⼤ How to make ⽤ use ?

  11. If ⼀ One by one ⼝ Oral 2 No 不 The realization of the same , So how to come to Autowire⼀ A specified implementation ?

  12. Spring Declarative transactions @Transaction annotation ⼀ It is usually written in what 什 What position? ? Throw out 了 abnormal Meeting ⾃ Auto roll back ? Is there any way to control it 不 Trigger rollback ?

  13. If you want to be in a Bean⽣ After generating and assembling, execute ⾏ That's ok 行⾃ since ⼰ My own logic , What can be 什 Well ⽅ The way is present ?

  14. SpringBoot Didn't put it in web Containers 器⾥ in 里 Why? 什 You can't run HTTP service ?

  15. SpringBoot If you want to make ⽤ use ⾃ Custom configuration ⽂ file ⽽ Instead of 不 just application.properties, What should I do 弄?

  16. SpringMVC in RequestMapping You can specify GET, POST⽅ Methods? ? How to designate ?

  17. SpringMVC If you want to output Object( example 例 Such as XXResult perhaps XXResponse) this The packing is JSON Output , What to do with 理?

  18. How to intercept SpringMVC It's abnormal , Then I do ⾃ Custom processing 理,⽐ For example, fight ⽇ Journal or packaging become JSON

MySQL

  1. If there's a lot of data to plug in ⼊ Enter into MYSQL What would you choose 什 Well ⽅ The way ?

  2. If the query is slow , You will think of the ⼀ One ⽅ What is the way 什 Well ? The index is ⼲ What do you do? ?

  3. If it's built 了⼀ A single column 列 Indexes , Find out 2 Column 列, Meeting ⽤ Use this single column 列 Index ?

  4. If it's built 了⼀ One contains more than one column 列 The index of , When you look up, it's just ⽤ It was used 了 The first ⼀ A column of 列, Can't you 不 can ⽤ use This index ? Look up three columns 列 Well ?

  5. Pick up the question , If where After the condition ⾯ There is ⼀ One i + 5 < 100 Can make ⽤ Use this index ?

  6. How to see if ⽤ Yes 了 Some index ?

  7. like %aaa% Can make ⽤ Use the index ? like aaa% Well ?

  8. drop、 truncate、 delete The difference between ?

  9. How do you usually monitor the database ? slow SQL How to check ?

  10. Is your database ⽀ Support emoji expression , If you don't 不⽀ Support , How to operate ?

  11. The amount of data in a single table in your database 量 How much is the ?⼀ In general, there are many ⼤ When you are big, query performance is urgent Dramatic decline ?

  12. The inquiry is dead 了, I want to find out ⾏ That's ok 行 The query process of ⽤ What to use 什 You order ? After finding out ⼀ Generally you Meeting ⼲ why ?

  13. How is the separation of reading and writing done ? What do you think middleware will do ? This operation has something to do with affairs What 什 What's the matter ?

  14. Has the sub database and sub table been made ? What is the online migration process like ? How to make sure the data is positive Yes ?

JVM

  1. What do you know or do you use online ⽤ What to use 什 Well GC Strategy 略? What does it have 什 What's the advantage , optimum ⽤ For what 什 Well scene ?

  2. JAVA Class loader 器 Include ⼏ several ? Between them ⽗ Father ⼦ What's the relationship like ? Parents' appointment machine What is the system 什 What do you mean ? What do you have 什 What's the benefit ?

  3. how ⾃ Customize ⼀ A classloader 器? You make ⽤ What have you used or what you are 什 You need to ⼀ One ⾃ since Defined class loaders 器 Do you ?

  4. What are the parameters of heap memory setting 什 Well ?

  5. Perm Space What's in it 什 Data ? Can cause OutOfMemory Do you ?

  6. do gc when ,⼀ An object in the memory of each Space What's the order of being moved in 什 Well ?

  7. Have you ever met OutOfMemory problem ? How do you deal with 理 Of this question ? Handle 理 What's in the process ?

  8. 1.8 after Perm Space What are the changes ? MetaSpace⼤ Big ⼩ The little default is ⽆ Infinite ? still What will you pass 什 Well ⽅ The way to specify ⼤ Big ⼩ Small ?

  9. Jstack yes ⼲ What's going on 什 Well ? Jstat Well ? If online programs periodically get stuck , You suspect that Can be gc As a result of , How would you investigate this problem ? Threads ⽇ journal ⼀ You usually look at what's in it 什 Well part ?

  10. StackOverFlow Have you ever encountered an exception ?⼀ You usually guess what it will be 什 Under the circumstances of being touched Hair ? How to specify ⼀ A thread stack ⼤ Big ⼩ Small ?⼀ How much do you usually write ?

Linux command

0. add to Java Study :1037935907

  1. ⽇ The journal is special ⼤ Big just wants to see the last 100⾏ That's ok 行 How to get 弄? If you want to ⼀ Keep watching ⽇ Continuous output of logs ,⽤ use What 什 You order ?

  2. If ⽇ journal ⼀ Output ,⼀ At the same time, I want to see if there is a keyword and how to do it in real time 弄?

  3. grep If you ignore 略⼤ Big ⼩ How to make lowercase 弄? Regular expressions ?

  4. vim Down ⼀ One ⾏ That's ok 行 What is it 什 Mo key ? Down 30⾏ That's ok 行 Well ? Jump to the ⽂ end of file ⼀ One ⾏ That's ok 行 What is it 什 Well ? Jump back What is it 什 Well ? What is the backward search 什 Well ?

  5. If there is one ⽂ Text ⽂ file , Use spaces as columns 列 The delimiter , If you want to count the third column 列⾥ in 里⾯ Every face How to deal with the number of occurrences of a word 弄?

  6. If you put it on ⾯ How to arrange the number of times the face appears 弄? Want to follow the order of the numbers themselves ⽽ Instead of 不 yes character string 串 The order of 列 How to get 弄?

  7. Linux environment variable 量 Why 什 As a separator ? environment variable 量 Through what 什 Command settings ?

  8. To someone ⽂ Document rights are limited ⽐ For example, set to 644 yes ⽤ What to use 什 You order ? This 6 What is it 什 What do you mean ?

  9. Linux Next ⾯ If you want to see the resources occupied by a process ⽤ What's the use situation ? System load⼤ Probably What do you mean 什 What do you mean ? Your online system load⼀ Generally how much ? If ⼀ One 4 Nuclear machine 器, You think more Less load yes ⽐ More normal ? top command ⾥ in 里⾯ Face to face ⼀ once 1 Will send ⽣ What's the matter 什 Well ?

  10. top command ⾥ in 里⾯ Noodles , Sometimes all the processes CPU send ⽤ The usage rate adds up to more than 100% How to get back to things ?

  11. What other commands are available to check system performance or find problems ? you ⼀ It's usually to see which ginseng Count ?

  12. Want to see a process open 了 Which? ⽹ What is network connection 什 You order ?⾥ in 里⾯ The state of face connection you ⽐ Compare Turn off ⼼ My heart ⼏ several ?

-- Partial topic

  1. Have you ever done Linux system parameter ⽅ Fang ⾯ Face optimization ,⼤ Maybe what has been optimized 什 Well ?

  2. system parameter ⾥ in 里⾯ There's a noodle called backlog Can ⽤ be used for ⼲ What's going on 什 Well ?

  3. see ⽹ Network connection found a lot of TIME_WAIT It could be something 什 Why ? Your answer is ⽤ What's the use of it 什 Yao impact ? What would you choose 什 What kind of ⽅ To reduce these TIME_WAIT

  4. May I introduce ⼀ once TCP Three grip ⼿ The process of the hand , If there's a ⽹ Network program , you ⽤ Use the third ⽅ Fang Of library To send data , You suspect this library There's something wrong with the data sent , So how to test Prove ? tcpdump Derived ⽂ File you ⼀ How to analyze it in general ?

  5. KeepAlive yes ⽤ be used for ⼲ What's going on 什 Well ? What's the advantage of this 什 Well ?

Redis

-- Development

  1. Cache penetration can introduce ⼀ For a second ? How do you think this problem should be solved

  2. How do you trigger caching more 更 new ? (⽐ For example, set the timeout time ( passive ⽅ The way ), ⽐ For example, more 更 The new time Wait for the initiative update)? If it's passive ⽅ How to control multiple ⼊ Enter into ⼝ At the same time, the port triggers a cache change 更 new ?

  3. You ⽤ use Redis What to do 什 Well ? Why? 什 Well, No 不⽤ Use something else KV Storage example 例 Such as Memcached, Cassandra etc. ?

  4. You ⽤ What to use 什 Well Redis client ? Redis⾼ Reasons for high performance ⼤ It can be said that ⼀ some ?

  5. What are you familiar with Redis Data structure of ? zset yes ⼲ What's going on 什 Well ? and set What do you have 什 What's the difference ?

  6. Redis Of hash, What is the specific command to store and retrieve 什 What's the name ?

  7. LPOP and BLPOP The difference between ?

  8. Redis There are ⼀ Some contain SCAN The command for the keyword is ⼲ What do you do? ? SCAN The amount of data returned 量 yes Fixed ?

  9. Redis Medium Lua Did you make ⽤ Used to ? Sure ⽤ What is it for 什 Well ? Why? 什 You can do this ⽤ use ?

  10. Redis Of Pipeline yes ⽤ be used for ⼲ What's going on 什 Well ?

-- Operation and maintenance

  1. Redis Persistence ⼤ There are about ⼏ several ⽅ The way ? aof and rdb What's the difference 什 Well ? AOF What do you have 什 What are the advantages and disadvantages Would you like some ?

  2. Redis Replication Of ⼤ What is the general process 什 Well ? bgsave The execution of this order ⾏ That's ok 行 The process ? -- Partial topic

  3. If there are many KV Data to be stored in Redis, But memory is not 不⾜ foot , Through what 什 Well ⽅ The way can be contracted Reduce memory ? Why? 什 Well, it can shrink ⼩ Small memory ?

  4. Redis in List, HashTable all ⽤ Yes 了ZipList, Why? 什 Will you choose it ? monitor 、 stability

  5. Business ⽇ What is the log through 什 Well ⽅ Way to collect ?

  6. Online machine 器 How to monitor ? Mining ⽤ What to use 什 Open source products or ⾃ Self developed products ? It's a minute level It's in seconds ?

  7. If you can find a way to collect ⼀ One JAVA The back end should ⽤ Performance data used , What do you care about ⽅ Fang ⾯ Noodles ? What would you choose 什 What kind of ⼯ Tools 、 Ideas 路 To collect ?

  8. ⼀ You usually tune ⽤ Use the third ⽅ Fang will not 不 Can monitor the tune ⽤ Use situation ?  Insert picture description here

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