Alibaba Interview The
first one: What does Alibaba ask in an interview? : (55 minutes)
1. What are the data structures that Java uses more frequently in development?
2Talk about your understanding of HashMap, the basic realization of the underlying principles, how does HashMap solve the collision problem?
Are these data structures thread-safe? If you answer that HashMap is thread-safe, then ask if you have a thread-safe map, and then ask the conurren package.
3. Are you familiar with JVM? Simply talk about the class loading process, what operations are performed in it? Asked about GC and memory management, have you done any related configuration in tomect?
4. Then I asked about the http protocol, the basic difference between get and post, followed by the tcp/ip protocol, three-way handshake, and window sliding mechanism.
5. Which databases are used in development? Answer mysql, what are the storage engines? Then I asked me about the usage scenarios of pessimistic locking and optimistic locking, and the principles of distributed cluster implementation.
6. Then I asked me the working principle of springmvc and mybatis, have you seen the underlying source code?
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JD Finance Interview
1. Dubbo timeout retry; Dubbo timeout time setting
2. How to guarantee the order of request execution
3. Distributed things and distributed locks (don’t have negative numbers in deductions)
4. Distributed session settings
5. Perform an operation, the first 50 times succeeded, the 51st failed a rollback b submitted the first 50 times, the 51st exception thrown, how to set up Spring in the ab scene (propagation)
6. What are the uses of Zookeeper
7, JVM memory model
8. Vertical and horizontal split of the database
9. How to pagination in MyBatis; how to set cache; MySQL pagination
10. Are you familiar with IO? The difference with NIO, the difference between blocking and non-blocking
11. Distributed session consistency
12. The idempotent design of the distributed interface "cannot be deducted repeatedly"
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Meituan Interview
1. Which project is you familiar with recently? Draw the project technical architecture diagram
2. What is the ratio of the old and young JVM generations?
3. The specific scenarios of YGC and FGC
4. What are the meanings of jstack, jmap, and jutil? How to troubleshoot JVM related issues online?
5. What are the specific meanings of the five parameters of the method of constructing the thread pool?
6. What should I do if a thread pool is processing services on a single machine if the power is suddenly cut off? (How to deal with the requests in the processing and blocking queue)?
7. What problems will arise when using unbounded blocking queues?
8. How does the interface handle repeated requests?
9. What is the specific treatment plan?
10. How to ensure the atomicity of shared variable modification?
11. Design an interface implementation class for external services, and implement load balancing and sequential polling mechanisms on the three hosts 1, 2, and 3 (corresponding to different IPs) (concurrency is considered)
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Didi Interview
1. Self-introduction, technical characteristics
2. What is the interest and what is the advantage
3. What is the relationship between jvm, jre and jdk?
4. The underlying principle of Dubbo, what is Zookeeper
5. The mechanism of cincurrentMap; TreeMap; Volatil keyword
6. Quick sort; breadth first search (queue implementation)
7. The avalanche of cache and the understanding of penetration?
8. Can the key of HashMap be repeated?
9. The difference between synchronized and lock?
10. What issues would you consider when developing a large-scale website?
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Conclusions
from this undercover interview From the interview questions, it can be seen that the current Internet company interview test sites are:
1. Performance tuning, algorithm data organization
2. Data security, interface idempotence, atomicity, etc. under high concurrency
3. Distributed collaborative and locked processing
4. Database sub-database sub-table, vertical split between projects
The technical points with high frequency are:
1.HashMap
2.JVM
3.Dubbo
4.Mybatis
5.Zookeeper
6.http tcp/ip