Architect Ali spent six months interviewing 19-year summary of finishing on GitHub, watching swept BATJ

Ali articles (only problem, not the answer we need to explore learning together)

• How to achieve an efficient way linked list in reverse order output?
• Known sqrt (2) is approximately equal to 1.414, requires no math library, seeking sqrt (2) after 10 decimal places.
• Given a binary search tree (BST), a small tree found the first node K.
• LRU cache mechanism to design and implement an LRU (least recently used) cache data structure, we should support what operations: get and put. get (key) - If the key exists in the cache, then get the key value (always positive), otherwise -1. put (key, value) - If the key does not exist, or insertion set value. When the cache reaches its capacity, it should make the project the least recently used set aside prior to insertion of the new project.
• About epoll and select the difference, which statement is true? (Multiple choice)

A. epoll and select all I / O multiplexing technology, can be achieved simultaneously monitor the status of multiple I / O events.

B. epoll higher efficiency compared to select, mainly based on its operating system supports I / O event notification mechanism, and select is based on a polling mechanism.

C. epoll support level trigger and edge trigger modes.

D. select can support parallel I / O is relatively small, and can not be modified.

• [Extension] that at high concurrent access, epoll use that kind of trigger to be more efficient? When using edge-triggered pay attention to what things?
• From the index structure innodb analysis of why the index key length is not too long?
• How MySQL data recovery to any point in time?
• NFS and SMB are the two most common NAS (Network Attached Storage) protocol, when a file system to simultaneously share to multiple host access via NFS and SMB protocol, which of the following statements is wrong :( multiple choice)

A. not have such an operation, a file system that is shared simultaneously by a plurality of host access NFS and SMB protocol.

B. Host a file or directory created by the user via the NFS protocol, another host b users can not be deleted by the SMB protocol.

C. in the same directory, file file.txt host a see through NFS protocol, host b by the SMB protocol also see the file file.txt, then they are the same file.

D. a host through the NFS protocol and the SMB protocol b host, the host can cache the data terminal, to enhance the performance of file access.

• After entering the ping IP hit enter, what will happen before the contract?
• Next time please explain why Luhan published romance, microblogging system will collapse, how to solve?
• The existing number of messages to be sent to subscribe to the customer, and there is a cluster (cluster variable number of nodes, the dynamic expansion will reduce capacity) to be responsible for a specific task to send messages, how to make the system complete sent as soon as possible? Please elaborate technical solutions!
• There are a number of meteorological stations, now need to obtain observations at these sites, and stored in the Hive. But the Bureau of Meteorology provides only api query, you can only query a single observation point. So if we can quickly and easily get to the data of all observation points?
• How to achieve two amounts of data are added (up to two decimal places)?
• Parallel open on some basic issues calculations.

How ◼ defined and calculated, please elaborate distributed memory to a shared memory model differences and implement (example code) programming line respectively?

◼ Please use MPI and OpenMP are achieved N processors sum of M variables?

◼ Please indicate permission to use SIMD instructions in the loop? Which means there vectorization optimization?

◼ Please explain what Amdahl's law is parallel efficiency and scalability of parallel algorithms? And explain the performance and scalability limitations, and finally please explain in a shared memory computer, the shared memory limitations? OpenMP is how to implement shared memory programming environment? MPI blocking and non-blocking reads and writes the difference?

• Calculate the XILINX VU9P force equivalent to the chip count how many TOPS, given calculations and formulas.
• A modern processor, probably a simple MOV instruction can be executed per second, how many, what are the main influence factors?
• Please analyze the relationship MaxCompute distributed products and technologies, big data to calculate the current market situation and development trend of platform products.
• Big Data platform for metadata management is how to understand, metadata collection management system is kind of how, what kind of impact on large data applications.
• You understand the technical differences, and system bottlenecks common trends and technologies such as Ali, and the Friends of Big Data platform, an overview of the storage and computational aspects.
• Big Data in the cloud processing the scene, running thousands of daily tasks, each task should be carried out IO read and write. Storage systems in order to better service, often to ensure that high-priority tasks take precedence. When multiple jobs or users to access storage systems, how to ensure the priority and fairness.
• The maximum frequency of the stack.
• Achieve FreqStack, a simulation of the operation of a data structure of type similar to the stack. FreqStack has two functions: push (int x), the integer x to push the stack. pop (), remove it and return to the stack of elements that appear most frequently. If more than one element most frequently, remove and return the element closest to the top of the stack. ◼ Example: push [5,7,5,7,4,5] pop () -> returns 5, because 5 is the highest frequency. Stack become [5,7,5,7,4]. pop () -> return 7, 5 and 7 is because the highest frequency, but the closest stack 7. Stack become [5,7,5,4]. pop () -> 5 returns. Stack become [5,7,4]. pop () -> Returns 4. Stack becomes [5,7].
• Given a list, the list of deleted countdown N nodes and the head node returns the list.

◼ Example: Given a list: 1-> 2-> 3-> 4-> 5, and n = 2. When the removed penultimate node, the list becomes 1-> 2-> 3-> 5 Description: to ensure a given n is valid. Requirements: Only once allowed to traverse the list.

• If you had to design a universal, support a variety of database-level backup and restore of the second system, how would you design?
• If you were to design a database support, data flow and processing of real-time flow of data between NOSQL and big data, what issues would you consider? How to design?
• Given an integer a and an integer array, it returns the index of the two arrays, two index points and plus numbers equal to a specified integer. Require optimal algorithm, space and time complexity analysis of algorithms
• If you give a new product, you will what to protect its quality?
• Please evaluate the results of the program?
• How to test a bike?
• How to determine whether the two lists intersect?

US group articles

• java virtual machine memory model
• Memory overflow generally occurs in the region? Permanent generation will not cause a memory leak?
• Framework of dynamic loading of classes to learn how?
• What are the general dynamic proxy implementations? Dynamic proxy scenarios What?
• Stack will not overlap? Stack overlap usually throw anything unusual? jvm where to set the size of the stack? What are the parameters set?
• Jvm used some command to view the status of all kinds of information?
• jvm garbage collection mechanism?
• java class loading mechanism? How to implement a custom class loader? FindClass difference with the loadClass?
• String, StringBuffer, StringBuilder difference? Corresponding usage scenarios?
• How to achieve immutable class?
• Shallow copy and deep copy? How to achieve deep copy?
• HashMap, HashTable, ConcurrentHashMap difference?
• CAS is a some kind of synchronization mechanism?
• NIO principles, which include several components?
• A brief reflection of java? Reflected in some places there are scenarios?
• spring loaded bean process?
• java thread pool? Several parameters meaning thread pool constructor? keepAliveTime explain?
• An interface going to call another five interface Each interface will return data to the calling interface, call interface to merge the data and return to the upper layer. Such a scenario may be used under certain categories and contract? How would you go to achieve such business scenarios?
• CountDownLatch and CyclicBarrier difference?
• What threaded locking way? Synchronization and locks difference?
• The role of the volatile keyword? Why AtomicLong without using Long? AtomicLong changed is how to achieve?
• mysql storage engine, which has several?
• sql optimization What place to start? Meaning a combination of the most left-aligned principles of the index?
• springmvc request processing workflow?
• spring of affairs how to use? Transaction rollback? Custom exception?
• Dirty read? Magic Reading?
• tcp four waved process? Why TIME_WAIT at least double the MSL time?
• get and post requests difference?
• Request cookie and a session?
• What open source middleware understand? Cache? Message? Distributed framework?
• Use some design patterns? Achieve Singleton pattern?
• Transaction database implementation principle of operation, how to do things between independence and other issues
• Dirty reads the database, phantom reads, non-repeatable reads principle reason arise, solutions
• Isolation level of the database, MVCC
• Optimistic locking, pessimistic locking, mutexes, read-write locks realization of the principle of distinction
• Thread of the life cycle
• Consistency of principle and application hash algorithm
• CAP principles
• CAS operation
• Distributed raft algorithm

Jingdong articles

• General sql injection how to find the link, how to test the injection point from the binary code sqlmap.
• masscan port scan detection rely on, why so fast? Please comparison.
• You wrote some small tools, you used the tool for you to do anything to modify.
• How to improve the scanning speed of the write python, talk about the understanding of the GIL lock.
• Do you think that you find a breakthrough impact is relatively large.
• What are the common network expansion.
• We have not played hardware security, to study how the degree?
• Anti reptile, if you is how anti-reptile, how to bypass anti-climbing measures. Use headless browser is detected, how to bypass?
• How nmap scan to scan. Contract and agreement, shake hands and do not shake hands, shake hands these agreements, some do not shake hands. How not to direct contact with each other to detect a target server port is open?
• There is no writing your own off yara scanning module, if you want to solve scan {k1: v1, k2: v2, k3: v3}, while ensuring the presence of a particular value k1 of v1 in, v2 specific value k2 appear, and k3, v3. How to achieve?
• xss what principle, how they achieve a similar beef xss platform. Since this implementation, how to solve cross-domain face?
• frequency limit ip, ip reputation model?
• What SCTP protocol is? How to use SCTP optimize network?

Redis interview frequently asked questions

1. What are the benefits of using Redis there?
2. redis memcached What are the advantages compared to?
3. redis common performance problems and solutions
4. There 2000w MySQL data, only the data stored in redis 20w, how to ensure that the data is hot data in redis?
5. zookeeper four types of znode
6. Redis and Memcache difference between what are?
7. Redis common performance problems are what? How to solve?
8. redis most appropriate scene
9. Redis synchronization mechanism to understand it?
10. What ever used Redis cluster, the cluster is the principle?

MySQL frequently asked interview questions

• What super key primary key foreign key is a candidate key
• Four characteristics of database transactions and meanings
• The role of the view, the view can change it?
• Difference drop, delete and truncate the
• Index works its kind
• Connection Type
• Database paradigm
• Database optimization ideas
• The difference between stored procedures and triggers
• Explain the SQL left join and right join.md

MongoDB interview frequently asked questions

1. What is MongoDB?
2. MongoDB which language is written?
3. MongoDB What are the advantages?
4. What is a database
5. What is a collection of
6. What is the document
7. And a relational database terminology MongoDB comparison chart
8. What is "mongod"?
9. What "mongod" parameters?
10. What is the "mongo"?
11. MongoDB database which command to switch?
12. What is non-relational database?
13. Non-relational database What type?
14. Why MOngoDB?
15. The use of MongoDB in which scene?
16. Namespaces in MongoDB What does it mean
17. What languages ​​are supported MongoDB.
18. How to create a new database in MongoDB?
19. How to view the list of databases in MongoDB?
20. MongoDB is fragmented What does it mean?
21. How do I view the use of MongoDB connection?
22. What is copy?
23. How to insert a document in the collection in MongoDB?
24. How to remove a database in MongoDB?
25. How to create a collection in MongoDB?
26. How to view a collection has been created in MongoDB?
27. How to delete a collection in MongoDB?
28. Why use analyzer in MongoDB?
29. MongoDB supports primary key foreign key relationship it?
30. What type of data MongoDB support?
31. Why data types using Code MongoDB?
32. Why Expression data type in MongoDB with Regular?
33. Why use Object ID type of data in MongoDB?
34. How to insert a document in the collection?
35. "ObjectID" What parts?
36. In MongoDb What is an index?
37. How to add an index?
38. MongoDB which alternative products?
39. How to check the collection of documents?
40. How you can format the output?
41. How to use AND or OR conditions set cyclic query documents?
42. How to update data in MongoDB?
43. How do I delete a document?
44. How to sort in MongoDB?
45. What is polymerization?
46. What is in MongoDB replica set
47. Mongodb internal storage characteristics and principles

Zookeeper interview frequently asked question papers

1. What zookeeper that?
2. zookeeper provides what?
3. zookeeper File System
4. zookeeper four types of znode
5. zookeeper notification mechanism
6. Which scenario zookeeper there?
7. zk naming service.
8. k configuration management services.
9. Zk of cluster management.
10. zk distributed lock
11. zk queue management
12. zk data replication
13. zk in zab works
14. How zk is to ensure the consistency of the order of things
15. server cluster working state zk
16. How zk is the election of Leader
17. zookeeper synchronization process
18. Distributed notification and coordination
19. zk mechanism of session

These are the chiefs on github took a year to sort out questions about Ali, Jingdong, the US group asked to interview other major companies, the answer to the above question is not only a problem, but for everyone to learn the subject reference, hoping to find upcoming interview readers of work or prepare for work quit readers to help friends. After forwarding concerned about the increase below the VX interview notes mentioned below can receive free information! Thanks trust!

But after nearly a year of consolidation, small part of the interview here have collected relevant information, the content may not be fully consistent with the appeal, but the data also includes a lot of knowledge, including basic knowledge, Java collections, JVM, multithreading concurrent, spring principle, micro-services, Netty and RPC, Kafka, diary, design patterns, Java algorithms, databases, Zookeeper, distributed caching, data structures, and so on.