Come on October! Summarize the Java interview questions that frequently appeared in BAT manufacturers in September (with answers)

Preface

Hahaha! It's finally the last day of September, and with full of excitement, tomorrow will be the National Day holiday!
So today bloggers zoom trick, finishing all the current manufacturers of high-frequency Java interview questions are all coming out!
The answer is placed at the end of the article , and the main article starts!

The interview questions are divided into: concurrent programming + JVM + SPRING + database + cache + network programming + distributed

Concurrent programming:

1. What is multithreaded concurrency and parallelism?
2. What is the thread safety issue?
3. What is the memory visibility issue of shared variables?
4. What is atomic operation in Java?
5. What is the CAS operation in Java, and the realization principle of AtomicLong?
6. What is Java instruction reordering?
7. What is the memory semantics of the Synchronized keyword in Java?
8. What is the memory semantics of the Volatile keyword in Java?
9. What is false sharing, why does it occur, and how to avoid it?
10. What are reentrant locks, optimistic locks, pessimistic locks, fair locks, unfair locks, exclusive locks, and shared locks?
11. Tell me about the implementation principle of ThreadLocal?
12. How does ThreadLocal work as a variable thread isolation method?
13. Talk about the implementation principle of InheritableThreadLocal?
14. How does InheritableThreadLocal make up for the fact that ThreadLocal does not support inheritance?
15. How is the internal implementation of CyclicBarrier different from CountDownLatch?
16. How does the Random class of the random number generator use the CAS algorithm to ensure the uniqueness of the new seed under multithreading?
17. How does ThreadLocalRandom use the principle of ThreadLocal to solve the limitations of Random?
18. How to use ThreadLocal to implement request scope scope bean in Spring framework?
19. The realization of the bottom layer of the lock in the concurrent package (understanding of AQS)?
20. Talk about the principle of exclusive lock ReentrantLock?
21. Talk about the principle of ReentrantReadWriteLock?
22. Understanding the principle of StampedLock?
23. Talk about the understanding of the principle of the non-blocking unbounded queue ConcurrentLinkedQueue based on the linked list?
24. How does the ConcurrentLinkedQueue internally use CAS non-blocking algorithm to ensure the thread safety of multi-threaded enqueue and dequeue operations?
25. The principle of LinkedBlockingQueue based on linked list.
26. How does the blocking queue LinkedBlockingQueue use two exclusive locks ReentrantLock and the corresponding condition variables to ensure the thread safety of multi-threaded first-in-queue and out-queue operations?
27. Analyze the use and principle of the countdown counter CountDownLatch in JUC?
28. What is the difference between CountDownLatch and the Join method of threads?
29. Tell me about the use of CyclicBarrier in JUC?
30. How is the internal implementation of CyclicBarrier different from CountDownLatch?
31. What is the internal implementation of Semaphore?
32. How does the concurrent component CopyOnWriteArrayList implement a concurrent safe List through copy-on-write?

JVM

1. Java memory allocation?
2. What is the structure of the Java heap?
3. What is Perm Gen space in the heap?
4. Talk about the role of each area?
5. Is there a memory leak in Java, briefly?
6. Java class loading process?
7. Describe the principle mechanism of JVM loading Class files?
8. What is a class loader?
9. What are the class loaders?
10. What is the tomcat class loading mechanism?
11. The class loader parent delegation model mechanism?
12. What is GC? Why is GC?
13. Briefly describe the Java garbage collection mechanism?
14. How to judge whether an object is alive?
15. The advantages and principles of garbage collection, and consider 2 types of recycling mechanisms?
16. What is the basic principle of the garbage collector?
17. Can the garbage collector reclaim memory immediately? Is there any way to proactively notify the virtual machine for garbage collection?
18. Deep copy and shallow copy?
19. What will System.gc() and Runtime.gc() do?
20. What is distributed garbage collection (DGC)? How does it work?
21. What is the difference between a serial collector and a throughput collector?
22. In Java, when can an object be garbage collected?
23. Briefly describe Minor GC and Major GC?
24. What are the methods of garbage collection in Java?
25. Tell me about the performance evaluation and test indicators you understand?
26. What are the commonly used performance optimization methods?
27. Talk about distributed caching and consistent hashing?
28. Synchronous and asynchronous? Blocking and non-blocking?
29. What is GC tuning?
30. What are the common asynchronous methods?

Spring

1. Why do we need a proxy model?
2. Talk about the advantages and bottlenecks of the static proxy model?
3. Understanding of the realization principle of Java interface proxy mode?
4. How to implement dynamic proxy using Java reflection?
5. The designated enhancement of the Java interface proxy mode?
6. Talk about the implementation of enhanced dynamic proxy for Cglib class?
7. How to understand the aspects of aspect-oriented programming?
8. Explain the simple comparison between OOP and AOP?
9. Explain the principle and difference between JDK dynamic proxy and CGLIB proxy?
10. Explain the implementation principle of Schema-based AOP in the Spring framework?
11. Explain how to implement transaction management based on AOP in the Spring framework?
12. Talk about the understanding of the design idea of ​​inversion of control?
13. How to understand Spring IOC container?
14. How does Spring IOC manage the dependencies between beans and how to avoid circular dependencies?
15. Understanding of dependency injection in Spring IOC container?
16. Talk about the singleton mode and advanced features of Spring IOC?
17. What is the difference between BeanFactory and FactoryBean?
18. What is the difference between BeanFactory and ApplicationContext?
19. How does Spring resolve circular dependencies during bean creation?
20. Talk about the design patterns in the creation of Spring Bean?

database

1. What storage engines does MySQL have? What's the difference?
2. What is the difference between Float and Decimal storage amount?
3. What is the difference between Datetime and Timestamp storage time?
4. What is the difference between Char, Varchar and Varbinary storage characters?
5. Compare the B+ tree index and the Hash index?
6. What are the MySQL index types?
7. How to manage MySQL index?
8. Understanding of Explain parameters and important parameters?
9. What are the pros and cons of indexing and index classification?
10. What is the difference between a clustered index and a non-clustered index?
11. How is B+tree optimized? What principles does the index follow?
12. What is the relationship between index and lock?
13. What other index types are there, and what are their advantages and disadvantages?
14. Talk about your understanding of Innodb affairs?
15. Talk about the characteristics of database transactions and potential problems?
16. What is the MySQL isolation level?
17. How many scenarios of transaction failure are there and how to solve them?
18. What are consistent non-locking reads and consistent locking reads?
19. How does Innodb solve phantom reading?
20. Talk about Innodb row lock?
21. What is deadlock and monitoring?
22. What are self-growth and locks, lock algorithms, lock issues, and lock upgrades?
23. How does the optimistic locking thread compensate for failure?
24. How to prevent deadlock and ensure data consistency in high concurrency scenarios (receiving red envelopes)?
25. Talk about lock concurrency in MySQL?
26. What is the basic idea of ​​query optimization?
27. Talk about MySQL read-write separation, database and table sub-database?
28. What impact does the table structure have on performance?
29. Talking about index optimization?
30. Talk about the principles of Sql optimization?
31. MySQL table design and specification?
32. Talk about several MySQL storage engine application scenarios?
33. What are the common optimization methods for MySQL?
34. MySQL commonly used monitoring?
35. MySQL bottleneck analysis?

Cache

1. What are the redis data structures?
2. Redis cache penetration, cache avalanche?
3. How to use Redis to implement distributed locks?
4. How to solve the problem of concurrent competition in Redis?
5. Several methods of Redis persistence, what are the advantages and disadvantages, and how are they implemented?
6. Redis's cache invalidation strategy?
7. Redis cluster, high availability, principle?
8. Redis cache fragmentation?
9. Redis's data elimination strategy?
10. Redis queue application scenario?
11. Distributed usage scenario (storage session)?

network programming

1. TCP connection and disconnection process?
2. The interactive process of HTTP protocol, the difference between HTTP and HTTPS, the interactive process of SSL?
3. What is the use of TCP's sliding window protocol?
4. What are the methods of HTTP protocol?
5. The basic process of Socket interaction?
6. Talk about the tcp protocol (connection establishment process, slow start, sliding window, seven-layer model)?
7. Webservice protocol (wsdl/soap format, the difference with restt protocol)?
8. Talk about the Netty threading model, what is zero copy?
9. TCP handshake three times, wave four times?
10. DNS resolution process?
11. How does TCP ensure reliable data transmission?

distributed

1. What is the CAP theorem?
2. Talk about CAP theory and BASE theory?
3. What is final consistency? How to achieve final consistency?
4. What is a consistent hash?
5. Talk about distributed transactions?
6. How to implement distributed locks?
7. How to implement distributed session?
8. How to ensure the consistency of the message?
9. Understanding of load balancing?
10. Forward proxy and reverse proxy?
11. How does CDN work?
12. How to improve the QPS and throughput of the system?
13. The underlying realization principle and mechanism of Dubbo?
14. Describe the detailed process of a service from being published to being consumed?
15. How does the distributed system do service governance?
16. How does the message middleware solve the problem of message loss?
17. How to deal with the failure of Dubbo's service request?
18. Understanding of distributed transactions?
19. How to achieve load balancing and what algorithms can be implemented?
20. What is the purpose of Zookeeper and the principle of election?
21. Talk about the vertical split and horizontal split of data?
22. The principle and applicable scenarios of zookeeper?
23. Zookeeper watch mechanism?
24. How to deal with the redis/zk node downtime?
25. How to achieve a unique serial number in a distributed cluster?
26. Which MQs have been used, how to use them, and what are the advantages and disadvantages compared with other mqs? Is the connection of MQ thread safe?
27. How to ensure that the data in the MQ system will not be lost?
28. List the conceivable database sub-database sub-table strategies?

to sum up

The above are the interview questions most frequently asked by Internet companies in September. Due to the limited length of the article, the answers are organized into documents for everyone to receive for free.

Interview question information collection: Click here to get it for free, password: CSDN

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