From the preparation before the interview to the summary after the interview, I personally feel that there are still things I want to summarize after getting the offer. Recently, I will share the interview with everyone. Because it has been a long time, there may be some omissions, which are all personal thoughts. Please forgive me if anything is wrong.
This interview topic includes: ActiveMQ, Dubbo, JVM, Kafka, Linux, memcached, MongoDB, MyBatis, MySQL, Netty, Nginx, RabbitMQ, Redis, Spring Cloud, Spring Boot, Spring MVC, Spring, SQL, Tomcat, zookeeper, Concurrent programming, multithreading, open source frameworks, design patterns, microservices, a total of 25 real interview questions
Note that the actual interview questions and guidance in the article, as well as some technical documents, etc., can all be shared with my readers and friends of this article for free.
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One, ActiveMQ articles
- 1. What is ActiveMQ?
- What should I do if the ActiveMQ server is down?
- What should I do if I lose the message?
- Persistent messages are very slow
- Uneven consumption of messages
- Dead letter queue
- Is the message retransmission interval and retransmission times in ActiveMQ?
Two, MySQL
- A table with an ID auto-incrementing primary key. After inserting 17 records, delete the 15, 16, 17 records, restart Mysql, and insert a record. Is the ID of this record 18 or 15?
- What are the technical characteristics of Mysql?
- What is the Heap table?
- What is the default port of Mysql server?
- How to distinguish FLOAT and DOUBLE?
- Distinguish between CHAR_LENGTH and LENGTH
- Please briefly describe the names of the four transaction isolation levels supported by InnoDB in Mysql and the differences between each level
- What is the usage of ENUM in Mysql?
- How to define REGEXP?
- What is the difference between CHAR and VARCHAR?
- What can be the string type of the column?
- How to get the current Mysql version?
- What storage engine is used in Mysql?
- What is the Mysql driver?
- What does TIMESTAMP do on the UPDATE CURRENT_TIMESTAMP data type?
- What is the difference between primary key and candidate key?
- How to use Unix shell to log in to Mysql?
- What is myisamchk used for?
- What are the method commands for MYSQL database server performance analysis?
- How to optimize the performance of mysql?
- How to control the maximum size of the HEAP table?
Three, Dubbo articles
- What protocols does Dubbo support, the application scenarios of each protocol, advantages and disadvantages?
- How to set Dubbo timeout time?
- Which registration centers does Dubbo have?
- What is Dubbo?
- What are the main application scenarios of Dubbo?
- What is the core function of Dubbo?
- The core components of Dubbo?
- Dubbo service registration and discovery process?
- Dubbo's architecture design?
- Dubbo's service call process?
- Zookeeper in Dubbo acts as the registry. If the registry clusters are all down, can publishers and subscribers still communicate?
- Dubbo service load balancing strategy
- How does Dubbo solve the security mechanism?
- The difference between Dubbo connection registration center and direct connection
- Dubbo communication protocol Why does the dubbo protocol use asynchronous single long connection
- RMI protocol
- Hessian Agreement
Four, JVM articles
- Talk about the main components of jvm? And its role?
- Talk about the jvm runtime data area?
- Tell me about the difference between stacks?
- What are queues and stacks? What's the difference?
- What is the parent delegation model?
- Talk about the execution process of class loading?
- How to judge whether the object can be recycled?
- What are the reference types in java?
- Tell me about what garbage collection algorithms does jvm have?
- Tell me about what garbage collectors jvm has?
- Tell me more about the CMS garbage collector?
- What are the new-generation garbage collectors and the old-generation garbage collectors? What's the difference?
- Briefly describe how the generational garbage collector works?
- Talk about jvm tuning tools?
- What are the commonly used jvm tuning parameters?
Five, Kafka articles
- Can Kafka be used separately from zookeeper? why?
- How many data retention strategies does Kafka have?
- Kafka has set 7 days and 10G to clear data at the same time. By the fifth day, the message reached 10G. What will Kafka do at this time?
- What can cause Kafka to run slower?
- What should I pay attention to when using Kafka cluster?
- What is the design of Kafka?
- What is the message format of Kafka stored on the hard disk?
- Kafka efficient file storage design features
- Kafka's ack mechanism
Six, Linux articles
- What is the meaning of user mode and kernel mode in Linux?
- How to apply for a large chunk of kernel memory?
- What are the main ways of communication between user processes?
- What are the main types of kernel locks in Linux?
- What are the functions to apply for kernel memory through the partner system?
- In which data structure is the operation function of the file or device stored?
- What are the system calls to create a process?
- What are the ways to call schedule() for process switching?
- Does the Linux scheduler schedule processes based on their dynamic priority or static priority?
- What kinds of devices are there in Linux?
- How to uniquely identify a device?
- Is the floating-point operation in Linux implemented by the application or by the kernel?
memcached articles
- How does memcached work?
- What is the biggest advantage of memcached?
- Compared with the query cache of MySQL, what are the advantages and disadvantages of memcached?
- Compared with the local cache of the server (such as PHP APC, mmap file, etc.), what are the advantages of memcached?
- What is the cache mechanism of memcached?
- How does memcached implement redundancy mechanism?
- How does memcached handle fault tolerance?
- How to import and export items in memcached in batches?
- I need to export and import items in memcached in batches, what should I do?
- How does memcached do authentication?
- What is the multithreading of memcached? How to use them?
- What is the maximum key length that memcached can accept?
- What restrictions does memcached have on the expiration time of items?
- Why is the size of a single item limited to 1M byte?
Seven, MongoDB articles
- What do you mean by NoSQL database? What is the direct difference between NoSQL and RDBMS? Why use and not use NoSQL database? Talk about several advantages of NoSQL database?
- What types of NoSQL databases are there?
- What is the most basic difference between MySQL and MongoDB?
- How do you compare MongoDB, CouchDB and CouchBase?
- What makes MongoDB the best NoSQL database?
- What are the nuances on 32-bit systems?
- Will journal playback encounter problems when the entry is incomplete (for example, there happens to be a midway failure)?
- What is the role of the analyzer in MongoDB?
- What is a namespace?
- How to perform transactions/locks?
- What is master or primary?
- When will the data expand to multiple shards
Eight, MyBatis articles
- What is the difference between #{} and ${} in mybatis?
- How many paging methods does mybatis have?
- Is RowBounds querying all results at once? why?
- What is the difference between mybatis logical paging and physical paging?
- Does mybatis support lazy loading? What is the principle of lazy loading?
- Tell me about the first level cache and the second level cache of mybatis?
- What are the differences between mybatis and hibernate?
- What executors does mybatis have?
- What is the realization principle of mybatis paging plug-in?
- How to write a custom plug-in for mybatis?
Nine, Netty
- What is the difference between NIO and AIO?
- What is the composition of NIO?
- What are the characteristics of Netty?
- The reason and solution of TCP sticking/unpacking?
- What kind of serialization protocols do you know?
- How to choose a serialization protocol?
- Netty's zero copy implementation?
- What are the high performance of Netty?
- NIOEventLoopGroup source code?
Ten, Nginx articles
- Please explain what is Nginx?
- Please list some features of Nginx
- Please list the differences between Nginx and Apache
- Please explain how Nginx handles HTTP requests
- In Nginx, how to use an undefined server name to prevent requests from being processed?
- What are the advantages of using a "reverse proxy server"?
- Please list the best uses of Nginx server
- Please explain what are the Master and Worker processes on the Nginx server?
- Please explain how you open Nginx through a port other than 80?
- Please explain whether it is possible to replace Nginx errors with 502 errors, 503?
- In Nginx, explain how to keep the double slash in the URL
- Please explain what is the role of ngx_http_upstream_module?
- Please explain what is the C10K problem?
- Please state what is the function of the stub_status and sub_filter commands?
- Explain whether Nginx supports compressing requests to upstream?
- Explain how to get the current time in Nginx?
Eleven, RabbitMQ articles
- What are the usage scenarios of rabbitmq?
- What are the important roles of rabbitmq?
- What are the important components of rabbitmq?
- What is the role of vhost in rabbitmq?
- How are rabbitmq's messages sent?
- How does rabbitmq guarantee the stability of the message?
- How does rabbitmq avoid message loss?
- What are the conditions to ensure the success of message persistence?
- What are the disadvantages of rabbitmq persistence?
- How many types of broadcasts does rabbitmq have?
- How does rabbitmq implement a delayed message queue?
- What is the use of rabbitmq cluster?
- What are the types of rabbitmq nodes?
- Is each node of rabbitmq a complete copy of other nodes? why?
- What happens if the only disk node in the rabbitmq cluster crashes?
- Does rabbitmq have any requirements on the stopping order of cluster nodes?
- What issues should be paid attention to when building a rabbitmq cluster?
12. Redis
- What is redis? What are the usage scenarios?
- What are the functions of redis?
- What is the difference between redis and memecache?
- Why is redis single-threaded?
- What is cache penetration? How to deal with it?
- What data types does redis support?
- What is the difference between redis and redisson?
- How to ensure the consistency of cache and database data?
- How many ways are redis persistence?
- How does redis implement distributed locks?
- What are the shortcomings of redis distributed locks?
- How does redis optimize memory?
- What are the redis elimination strategies?
- What are the common performance problems of redis? How to solve it?
Thirteen, Spring Cloud/Boot
- What is spring boot?
- Why use spring boot?
- What is the spring boot core configuration file?
- What types of spring boot configuration files are there? What is the difference between them?
- What are the ways to achieve hot deployment with spring boot?
- What is the difference between jpa and hibernate?
- What is spring cloud?
- What is the function of spring cloud circuit breaker?
- What are the core components of spring cloud?
14. Spring/Spring MVC
- Why use spring?
- Explain what is aop?
- Explain what is ioc?
- What are the main modules of spring?
- What are the common injection methods for spring?
- Are beans in spring thread-safe?
- 96. What scope of beans does spring support?
- What are the ways to automatically assemble beans in spring?
- What are the spring transaction implementation methods?
- Talk about spring's transaction isolation?
- What are the components of spring mvc?
- What is the purpose of @RequestMapping?
- What is the role of @Autowired?
15. SQL
- A table with an ID auto-incrementing primary key. After inserting 17 records, delete the 15, 16, 17 records, restart Mysql, and insert a record. Is the ID of this record 18 or 15?
- What are the technical characteristics of Mysql?
- What is the Heap table?
- What is the default port of Mysql server?
- Compared with Oracle, what are the advantages of Mysql?
- How to distinguish FLOAT and DOUBLE?
- Distinguish between CHAR_LENGTH and LENGTH?
- Please briefly describe the names of the four transaction isolation levels supported by InnoDB in Mysql and the differences between each level?
- What is the usage of ENUM in Mysql
- How to define REGEXP?
- What is the difference between CHAR and VARCHAR?
- What can be the string type of the column?
16. Tomcat articles
- What is the default port of Tomcat and how to modify it?
- What kinds of connector operating modes (optimization) does Tomcat have?
- How many deployment methods are available for Tomcat?
- How does the Tomcat container create an instance of the servlet class? What principle was used?
- How to optimize Tomcat?
- Memory tuning
- Garbage collection strategy tuning
- Shared session processing
- Add JMS remote monitoring
- About the number of Tomcat sessions
- Monitor Tomcat's memory usage
- The loading status of the printing class and the recycling status of the object
- Tomcat complete process of a request
- Tomcat working mode
Seventeen, zookeeper articles
- What is ZooKeeper?
- What does ZooKeeper provide?
- Zookeeper file system
- Four types of znode
- Zookeeper notification mechanism
- What did Zookeeper do?
- zk's naming service (file system)
- zk configuration management (file system, notification mechanism)
- Zookeeper cluster management (file system, notification mechanism)
- Zookeeper distributed lock (file system, notification mechanism)
Eighteen, concurrent programming articles
- Have you ever used Synchronized and what is its principle?
- You just mentioned acquiring a lock on an object. What is this "lock"? How to determine the lock of an object?
- What is reentrancy? Why is Synchronized a reentrant lock?
- What optimizations has JVM made to Java's native locks?
- Why is Synchronized an unfair lock?
- What is lock elimination and lock coarsening?
- Why is Synchronized a pessimistic lock? What is the realization principle of optimistic locking?
- What is CAS and what are its characteristics?
- Is optimistic locking necessarily good?
- Compared with Synchronized, how is the implementation principle of reentrant ReentrantLock different?
- Please talk about the AQS framework
- Please compare the similarities and differences between Synchronized and ReentrantLock in as much detail as possible
- How does ReentrantLock achieve reentrancy?
- In addition to ReentrantLock, what other concurrency tools in JUC have you been exposed to?
- Please talk about ReadWriteLock and StampedLock
- How to synchronize the threads of Java with each other? What synchronizers do you know about? Please introduce separately
- CyclicBarrier and CountDownLatch look very similar, please compare
- How is the thread pool implemented in Java?
- Several core construction parameters for creating thread pools
- How are the threads in the thread pool created? Was it created at the beginning with the start of the thread pool?
- Since it is mentioned that different thread pools can be created by configuring different parameters, what thread pools are implemented by default in Java? Please compare their similarities and differences
- How to submit threads in the Java thread pool?
- What is Java's memory model, and how does each thread in Java see each other's variables?
- Please talk about the characteristics of Volatile and why it can guarantee the visibility of variables to all threads?
- Since Volatile can guarantee the visibility of variables seen in the county, does it mean that operations based on Volatile variables are concurrent and safe?
- Please compare the similarities and differences between Volatile and Synchronized
- Please talk about how RhreadLocal solves concurrency safety?
- Many people say that you should use TheadLocal with caution. Talk about your understanding. What should you pay attention to when using TheadLocal?
Nineteen, multi-threaded articles
- Now there are three threads T1, T2, and T3. How do you ensure that T2 is executed after T1 is executed, and T3 is executed after T2 is executed?
- Write code in Java to solve the producer-consumer problem
- Using Java to program a program that will cause a deadlock, how would you solve it?
- What are atomic operations and what are atomic operations in Java?
- What is the key to volatile in Java? How to use it? How is it different from the synchronized method in Java?
- How will you use threaddump? How will you analyze Thread dump?
- Why do we execute the run() method when we call the start() method, and why can’t we call the run() method directly?
- How do you wake up a blocked thread in Java?
- What is the difference between CycliBarriar and CountdownLatch in Java?
- What are the common problems you encounter in a multithreaded environment? How did you solve it?
Twenty, open source framework articles
- What is the difference between BeanFactory and ApplicationContext?
- The life cycle of Spring Bean
- How to implement Spring IOC?
- Talk about Spring AOP
- Spring AOP implementation principle
- Dynamic proxy (cglib and JDK)
- Spring transaction implementation
- The underlying principle of Spring transaction
- How to customize annotations to implement functions
- Spring MVC running process
- Spring MVC startup process
- Spring's singleton implementation principle
- What design patterns are used in the Spring framework
- Why choose Netty
- Talk about the usage scenarios of Netty in business
- Native NIO has an epoll bug in JDK 1.7
- What is TCP sticking/unpacking
- TCP sticking/unpacking solution
- Netty threading model
- Talk about Netty's zero copy
- Netty internal execution process
21. Design Patterns
- Please list several commonly used design patterns in JDK?
- What is a design pattern? Have you used any design patterns in your code?
- What is the singleton design pattern in Java? Please write a thread-safe singleton pattern in Java
- What are the main benefits of using the factory model? Where is it used?
- Give a decorator design pattern implemented in Java? Does it act on the object level or the class level?
- In Java, why is it not allowed to access non-static variables from static methods?
- Design an ATM machine, please tell me your design ideas?
- In Java, when do you use overloading and when do you use rewriting?
- Give examples to illustrate when you would prefer to use abstract classes instead of interfaces?
Twenty-two, microservices
- How to separate the front and back ends
- Which frameworks for microservices
- Talk about the implementation principle of RPC
- Talk about the realization principle of Dubbo
Reader benefits
This article organizes 25 types of interview questions for everyone, and also organizes some learning materials.
If you need to get the answers to the interview questions and learning materials of this article, you can click here to get it~
If you need to get the answers to the interview questions and learning materials in this article, you can click here to get it~