There are a total of interview bytes, Meituan, Baidu, Tencent, Ali, WeChat Pay, Douyu, NetEase Cloud, and Kuaishou throughout the autumn recruitment .
But the offers I got were three Baidu, Ali, Byte, and I review the entire autumn recruits\spring recruits in a flashback.
The editor has also sorted out the interview questions and answers for the entire autumn recruitment. Click here to get it for free, the code: CSDN , there are more interview topics and videos from big factories.
Byte Beat 2020-9-16 (Offer)
one side
1. Are java annotations executed at runtime or at compile time? Will there be annotated information in the bytecode?
2. Talk about a put call method at the bottom of HashMap
3. Talk about red and black trees
4. Talk about the dynamic proxy (all three) how to implement the dynamic proxy of the RPC framework, have you ever thought about it (no, it should be Dubbo SPI)
5. Exchange coins
6. Preorder traversal of binary tree
7, thread pool
Two sides
1. Talk about asynchronous IO (AIO, BIO, NIO)
2. Talk about multiplexing (select\poll\epoll)
3. Kernel mode and user mode
4. Handwriting a thread pool (obviously not)
5. Copy linked list
6. Tiger and sheep problem
7, talk about Java locks
8. Talk about the consistent hash algorithm
Three sides
1. Talk about the optimization points and bugs of the project
2. Given an array, find that i<j<k and nums(i)<nums(j)<nums(k)
3. Get rainwater
4. Tell me about the points that you find interesting in the learning process
Meituan 2020-9-14 (hanging on one side)
1. What's the difficulty of seckill
2. Talk about spike current limiting, downgrade, and fuse (downgrade should be to close part of non-core business)
3. What will you do if you open a new version (do distributed, forget to say do distributed transactions)
4. If a JVM is OOM every one hour, where will you troubleshoot?
5. Combine the two arrays (in fact, you can use the swap strategy to reduce memory overhead)
6. What is the division of service (business, code amount)
7. What to do if the data is inconsistent
Interview information: Click here to get it for free, password: CSDN , there are more interview topics and videos from major companies!
Baidu 2020-9-10 (Offer)
one side
1. Talk about the exception system of java
2. The structure of jvm (PC, heap, virtual machine stack, local method stack) where memory overflow occurs (except PC), have you understood the runtime constant pool?
3. Talk about the difference between synchronized synchronization method and synchronized static method. When it comes to object headers, what's inside
4. The role of volatile
5. Talk about collections and red-black trees
6. What is the current limit used (the server current limit made by guava package)
7. What instructions are used for linux copy and move, and what is used between servers
8. Distributed hash of redis
9. Do you understand ThreadLocal (deduct the source code directly)
10. How many reference types are there (strong and weak)
11. equal and hashcode (this is the 1.6 specification)
12. Mysql talks about the difference between rr and rc (readview and mvcc talk about it)
13, talk about garbage collection algorithm and gcroot
Two sides
1. What is the difference between an array and a linked list
2. 20 billion records, each record has a unique id, how to speed up the query, 16G memory, available disk
3. Algorithm: determine a tree in the first middle order
4. Chat project
5. Are current limiting and downgrade the same thing?
6. What needs to be considered in the rpc framework
7. Do you understand microservices? Why use microservices
Three sides
1. Talk about internship
2. Impressive college things
3. Difficulties encountered
4. Chat project
Tencent CSIG 2020-9-10 (two sides hanging)
one side
1. Talk about the exception system of java
2. Talk about the http message format (first line + header + blank line + message style) talk about the header
3. Talk about the parameters of jvm
4. Talk about the redis message subscription and publishing mode (no) What data structure does redis have (5) What data structure does the ranking have (sorted set) Talk about the cluster mode of redis (three modes, master-slave, sentry, cluster)
5. Talk about the difference between http1/2
6. The difference between tcp and udp
7. Talk about how the project can be highly available and stateless
8. Source station detection scheme
9. Do you know the MTU? What should I do if the UDP header is too large (it will be fragmented, the MTU defaults to 1500)
Two sides
1、讲讲String、StringBuilder、StringBuffer
2. How to limit current
3. Coroutines and threads
4. What is the GPMS of go language (a little talk)
5. Can char store Chinese (should) how many bytes in Chinese (fuck, I answered 3, in fact utf-8 is like this) What is the relationship between unicode and utf-8 ( Unicode is "character set" UTF-8 is the "encoding rule")
6. The underlying source code of guava's current limiting component
7. How to design a go error (the bottom layer is an interface)
8. Red-black tree and AVL tree
9. How to design a hash table for arrays and linked lists (refer to hashmap) and how to optimize (using red-black trees)
10. After optimization, where is the bottleneck? (Tomcat, redis, mysql, mq)
11. Talk about the fast queue (optimized talk)
12、sychronized
13. Two storage engines of mysql
Interview information: Click here to get it for free, password: CSDN , there are more interview topics and videos from major companies!
Ali 2020-9-9 (Offer)
one side
1. Let’s talk about atomic, what are the methods of unsafe, can CAS use AtomiReferrence to solve the ABA problem?
2. Talk about volatile (sequence of visibility)
3. Talk about synchronized (objectmonitor). Why is synchronized a heavyweight lock? Is ReentranLock a heavyweight lock
4. Talk about the difference between ReentranLock and Synchronied
5. Innodedb and myisam of mysql (table-level locks, transactions)
6. What is the difference between a clustered index and a non-clustered index
7. How does mysql implement transaction rollback (undolog and redolog, let’s talk about an update process)
8. Do you understand MVCC (using undolog+readview to implement, talk about readview, and then talk about the difference between repeatable reading and reading submitted)
Two sides
Horror scene question
Three sides
1. Hash conflict resolution
2. Modeling scenario questions, no
3. Red and black trees
4. Talk about internship projects and self-made projects
5. Character
6. Books to read
Intersection
1. Talk about internship
2. Books to read
3. Talk about the distributed transaction of spike
WeChat Pay 2020-9-4 (hang on one side)
1. Moments of friends (and check collection)
2. lc600 does not contain consecutive 1 non-negative integers
3. Atm first deducts money or vomits money first (actually, it should vomit money first, then lock him and reconcile)
4. Do you understand the semaphore and mutexes of the operating system (one has resource number, one does not)
5. If mysql is abc joint index, then b will query and use the index (should not go)
6. What is the probability of a stick forming a triangle (analyzing the other two segments x, y, axy and finally getting 1/4)
7. Which sorts are stable (merge, insert, forget to sort by bubble)
Fighting fish 2020-8-28 (hr noodle hanging)
one side
1. The difference between operating system process and thread, process communication
2. JVM structure, OOM
3. Have you learned about tomcat (no) have you tuned it (no)
4. How to do distributed session
5. If you upload a large file of 15m, and set the maximum file of 10m in spring, how to deal with the error is to throw an exception on the tomcat side (look at the log first to see where the problem is, == Interviewer: just say that the demand can't be done == )
6. Spring's IOC and AOP
7, the linked list is reversed
8. Signal and semaphore (signal seems to be the underlying thing, semaphore is a synchronization mechanism, == signal: (signal) is a way to handle asynchronous events. Signal is a more complex communication method, used to notify the receiving process When a certain event occurs, in addition to being used for the process, it can also send a signal to the process itself ==)
Two sides
1. Project
2. Redis data structure, talk about skip table
3. At the bottom of hashmap, a put process (forgot to talk about expansion)
4. mysql master-slave replication
5. The difference between synchronized and reentrantlock, talk about AQS
NetEase Cloud 2020-8-14 (hr face-to-face)
one side
1. Project
2、String StringBuilder StringBuffer 区别
3. The difference between delete and drop
4. Poor index (frequent changes)
5. Talk about the garbage collection algorithm (copy, mark removal, mark sorting) the entire garbage collection process (new generation permanent generation)
6. Give a few examples to determine whether the index is invalid
7. The difference between sleep and wait (will the lock be released, timeout, thread status)
8. The difference between synchronized and volatile (just talk about the difference)
9. Talk about hashmap (the whole process of put, the difference between 1.7 and 1.8)
10. How does mq ensure that the message is not lost (before delivery, during delivery, after delivery)
11. Redis breakdown (blon filter and return empty object)
12. Redis and mysql data are inconsistent (delete and then modify)
13, talk about java thread pool
14. Talk about the JVM garbage collection algorithm and the process (three algorithms, the entire garbage collection process)
15. Talk about common Linux commands (hidden?)
16. The usefulness of binlog and its application scenarios.
Two sides
1. Chat project
2. Redis replacement algorithm
3. Design a comment system
Kuaishou 2020-8-11 (hanging on three sides)
one side
1. Talk about the practice optimization code (optimization warning)
2. Talk about spike, how to deal with the inconsistency between redis and database
3. The role of RabbitMQ (only for decoupling)
4. Talk about Redis's RDB and AOF. What scenarios are applicable?
5. Talk about ConcurrentHashMap
6. What are the characteristics of the mysql isolation level (repeatable reading) you use (repeatable reading, solving phantom reading) and how to solve phantom reading (MVCC and gap lock) and how the gap lock is on both sides
7. Talk about garbage collection mechanism (talk about 7 garbage collectors)
8. Talk about avl trees and red-black trees
9. The difference between b+ tree and b tree (can be range query) b tree can also be range query, such as middle order traversal to query (I think it is traversed more often)
10. Algorithm: Reverse order pair
Two sides:
1. Talk about a bunch of project background
2. ArrayBlockingQ and LinkedBlockingQ application scenarios How is ArrayBQ implemented (circular queue) SynchronousQueue application scenarios (==unclear==)
3. For http1.0 1.1 2.0, if http2.0 has multiple requests in one connection, will one request block cause all requests to block, will there be a request block that blocks the entire link?
4. How does TCP get the appropriate congestion value (slow start, first 2 times, then self-increase, and finally halved) to make congestion on the client side or on the server side? So where is the congestion window controlled (server side)
5. The biggest difference between AVL tree and red-black tree (number of rotations, more suitable for adding, deleting, checking and modifying) has it been tested? (No)
6. B-tree and B+-tree, why is the efficiency of querying B-tree slow (because it is not balanced, and range query cannot be done) What will happen if it is used for range query (I feel that the efficiency will be lower) Why not use red-black tree? (Multi-forked, the essential reason is that the height of the tree will be low!)
7. Algorithm: an array, formed by two ordered sequences, such as 1 3 5 2 4 6
Three sides
1. Talk about the memory management of jvm
2. Talk about the project and understand the bottom layer of the Tencent project?
3. Do you understand the operating system memory management?
4. What should I do if there are too many items in the spike?
5. Character advantages and disadvantages
6. Design a data structure, the characters that have been out of the queue the most times in the queue (a hash, a queue, if it is concurrently transformed into a concurrent container, if the distributed is transformed into a distributed container)
7. Internship
Baidu 2020-7-25 (hang on one side)
1. Internship experience
2. What are the characteristics of mysql's Innodb (Speaking of transactions, the entire update process, == forgot to say row lock ==)
3. How many bytes are the int of mysql (damn, == I didn't expect it, 4 bytes ==) For example, what is the difference between int(10) and int(5)
4. Talk about the process of Synchronized lock expansion (no lock, partial lock, lightweight lock, heavyweight lock)
5. What are the new features in 1.8 (not mentioned here) and what changes in the memory structure? (Permanent generation removed) Why should permanent generation become metaspace
6. Do you understand JVM optimization? Talk about optimization parameters
7. What is the difference between install and package of maven? What is the difference between realease version and snapshot version
8. How many workspaces does git have? (Three) Have you heard of reset?
9. The difference between clustered index and sparse index, why does Innodb have to have a primary key? == (Because identifying a piece of data is unique, and it is different from MyISAM, its data exists together, only through the primary key to obtain the unique)
10. How to optimize the index (explain) how to see (see id, type, key, possible key extra) Is there any more? (Gone)
11. Open scene questions and design an order system (load, cache, sub-database and sub-table, message queue)
12. Give a specific plan, order system (1, directly use db 2, asynchronous distributed transactions to deduct inventory 3, distributed lock 4, segmented lock)
13. How to look at PrintGCDetail (how much memory is there after the new generation garbage collection, and how much memory is there after the old generation is collected)
to sum up
Looking back on the entire autumn move, I found that there was still a big lack of ability, and some even failed at once.
So the editor has sorted out all the interview questions and answers! Learn to go to the interview now
Click here to receive it for free, the secret code: CSDN , there are more interview topics and videos from major companies!
