Ali, headlines, and pieces of the interview experience

I interviewed a number of companies, visit the company feels most points are the same, so their experiences down, hoping to give'm looking for a friend looking for work or prepare a little help. In addition, Ali also currently doing the interviewer's job seekers from identity becomes the interviewer, look at problems in many ways not the same, so below both the perspective of job seekers, but also the perspective of the interviewer.

Interview Process

Large companies generally have a 3-4 round technical, HR faces one of. On Ali, I experienced a total of four technical side, the first two rounds is the main basis for asking and project implementation, the first three are intersecting faces, two interviewers, mainly to ask project implementation and development. The first four are departments face the boss, asked to understand some of the major infrastructure, technology and business, personal development more abstract things.

HR surface is mainly chat with you, look at your personal stability, values, initiative, and the like, are generally not linked to HR person, but many people in the HR side hung up , the reason is not in your HR the faces of the poor (a few exceptions), but before you show a few faces in general, be higher than 60 points (so not directly linked to you in front of the interview), but it did not reach 80 points , this time the company based hc, talent ratio, and multiple dimensions compared to other candidates and other considerations, the final decision whether to give you offer.

Also said to be under special is that today's headlines on the study of algorithms will be more, I face the four techniques, each round will ask 1-2 questions algorithms, probably leetcode on easy and medium difficulty. So the best students want to go brush headline title.

Note that the point

1. Resume one to two is the best, the project experience to write about 2-3 on the same subject, be sure to write the most highlights of the project
2. Starting time work experience to write clearly, while large companies have back tone, do not merge or omit some relatively short period of work experience , the impact may not be just the interview, but later may not get into this company
3. For the interviewer's question, to think clearly before you answer, if you feel that the time required may be relatively long, can be said that the idea of ​​my thinking, my next class finishing with the interviewer
4. Problems encountered will not directly say no, do not pretend to understand
5. Compare encounter problems identified, there must be confident that the interviewer may sometimes deliberately skeptical tone to examine you
6. During the interview pay attention to speech rate and articulation , after I do the interviewer, found that many people tend to speak quickly, or slurred speech, also cause problems that would otherwise make the interviewer feel that you did not answer the point on (in particular, telephone surface)
7. The interview process can confidently but do not dispute with the interviewer
8. Interview after interview results do not directly ask
9. Interview Be confident but not arrogant, once I asked a candidate to say hashmap is well known, the result does not need to be re-calculated hash ignorant when asked to force the hashmap expansion. For many people, there is always a way to put the interviewer ask you pour.
10. After each interview are summarized there are bad places which answer , what knowledge are blind, to get rid of.
11. When asked why want a new job, because of the development from their own point of view, rather than Tucao former company .

The most important thing, do not fail a few times since the interview began to doubt yourself, always remember that the strength of the results of the interview = + luck . Sometimes you may be good at something the interviewer would not, so he could not spend a lot of time to ask what he do not know; sometimes he may ask you you will, but probably because the other questions are asked, tone and other reasons, a is not smooth.

The study went on to say related technologies

basis

The following are finishing the interview I think it will often be investigated to the point of knowledge, incomplete, but most of them are common interview questions.

java foundation

set

The collection is divided into two blocks: Thread safety in non-thread-safe collection and under java.util java.util.concurrent package collection.

List

ArrayList and LinkedList implementations and differences

Map

• HashMap: to understand the data structures, how to hash conflict resolution (list and red-black tree), the timing of expansion, optimization rehash of time to avoid expansion
• LinkedHashMap: understand the basic principles, what two orderly, how to use it to achieve LRU
• TreeMap: understand the data structure to see why the key target must be to achieve Compare the interface, how to use it to achieve consistent hashing

Set

Set basically achieved by a corresponding map, look like simple

common problem

1. How to hash hashmap resolve the conflict, why hashmap in the list need to turn into a red-black tree?
2. hashmap When will trigger the expansion?
3. Why concurrency problem when there is infinite loop hashmap before jdk1.8?
4. When hashmap expansion need to be calculated once for each entry hash it?
5. Why hashmap array length to ensure a power of 2?
6. How to implement LRU with LinkedHashMap?
7. How to achieve consistency with the hash TreeMap?

Thread-safe collection

Collections.synchronized

Understand the implementation principle

CopyOnWriteArrayList

Understanding replication mechanisms write, understand its application scenarios, think about why no ConcurrentArrayList

ConcurrentHashMap

Understand the implementation principle, to do when the expansion optimization, compared with the HashTable.

BlockingQueue

了解LinkedBlockingQueue、ArrayBlockingQueue、DelayQueue、SynchronousQueue

common problem

1. How ConcurrentHashMap is to improve performance in ensuring the safety of concurrent simultaneously?
2. How ConcurrentHashMap is to allow multiple threads at the same time to participate in the expansion?
3. LinkedBlockingQueue, DelayQueue is how to achieve?
4. How CopyOnWriteArrayList is to ensure thread-safe?

Complicated by

synchronized

Understand the difference biased locking, lightweight lock, concept and upgrade heavyweight lock mechanism, as well as and the ReentrantLock

CASE

AtomicInteger understand the implementation principle, CAS application scenarios, how optimistic locking

AQS

Understand the internal implementation AQS, and rely on synchronization classes such as AQS achieve ReentrantLock, Semaphore, CountDownLatch, CyclicBarrier etc.

ThreadLocal

ThreadLocal usage scenarios and understand the internal implementation

ThreadPoolExecutor

Work for the thread pool and set several important parameters

common problem

1. Difference synchronized with the ReentrantLock?
2. The difference between optimistic and pessimistic locking in?
3. How to implement an optimistic locking?
4. AQS is how to wake up the next thread?
5. How to achieve equity and non-equity ReentrantLock lock is how to achieve?
6. CountDownLatch and CyclicBarrier difference? What works best scene?
7. What should be noted when applicable ThreadLocal? For example, a memory leak?
8. Submit to talk about what a thread pool task will happen?
9. How to set several parameters thread pool?
10. Non-core thread pool thread when it will be released?
11. How to troubleshoot a deadlock?

I

Learn the difference between BIO and NIO understand multiplexing mechanism

common problem

1. Synchronous blocking, non-blocking synchronous, asynchronous difference?
2. select, poll, eopll the difference?
3. BIO and the difference between java NIO?
4. What refactor threading model?

JVM

GC

Garbage collection basic principles, several common characteristics of the garbage collector, focused on understanding the CMS (or G1) and a number of important parameters

Memory area

Jvm memory can say clearly divided

common problem

1. CMS GC recovery which is divided into several stages? They were done anything?
2. What are the important parameters of CMS have?
3. Concurrent Model Failure and ParNew promotion failed what happens?
4. CMS advantages and disadvantages?
5. What GC tuning done?
6. Why is divided into the old and the young generation's?
7. Why the young generation is divided into eden, survivor region?
8. Why the young generation uses a replication algorithm?
9. Why old's use of the mark is clear, mark Collation Algorithm
10. Under what circumstances the use of external memory heap? Pay attention to what?
11. How external heap memory is recovered?
12. jvm memory zoning is what?

Spring

bean life cycle, circular dependencies, spring cloud (such as projects have used) to achieve the AOP, spring transaction propagation

common problem

1. java dynamic proxy cglib difference and dynamic agent (often used in conjunction with the spring so they asked up here)
2. spring bean in the life cycle of what?
3. What kind of problems have circular dependency injection and constructor injection property?

Dubbo (or other frame Rpc)

RPC framework as a common understanding of Dubbo implementation: service discovery, routing, asynchronous calls, limiting downgrade, failure retry

common problem

1. How Dubbo do load balancing?
2. How do Dubbo limiting downgrade?
3. How Dubbo elegant service offline?
4. How Dubbo asynchronous calls?

RocketMq (or other message middleware)

A common understanding of messaging middleware such as RocketMq implementation: how to ensure high availability and high throughput, message sequence, repeated consumption, transaction messages, delay messages, dead letter queue

common problem

1. How RocketMq ensure high availability?
2. How RocketMq ensure high throughput?
3. RocketMq news is ordered it?
4. How to order local news RocketMq is guaranteed?
5. Implementation Mechanism RocketMq transaction messages?
6. RocketMq be a problem repeated consumption of it? How to solve?
7. What level of delayed messages RocketMq support? How to achieve it?
8. RocketMq is a push model or pull model?
9. Consumer load balancing is kind of how?

Redis (or other caching system)

redis working model, redis persistence, redis expired elimination mechanism, redis common form of distributed clusters, distributed lock, buffer breakdown, avalanche cache, cache coherency problem

common problem

1. Why redis high performance?
2. How to use single-threaded multi-core cpu redis machine?
3. redis cache elimination strategy?
4. How redis persistent data?
5. redis which has several data structures?
6. redis clusters, which has several forms?
7. There are massive key and value are relatively small data, how to store it in a more efficient memory in redis?
8. How to ensure data consistency and redis DB in?
9. How to solve the cache and cache penetrate the avalanche?
10. How to implement a distributed lock with redis?

Mysql

Transaction isolation level, locks, data structures, indexes, clustered indexes and non-clustered index, the leftmost matching principle, query optimization (explain commands)

common problem

1. Mysql (innondb the same below), which has several transaction isolation level?
2. What are the different transaction isolation level locks will be added?
3. Mysql row lock, the table lock, the lock gap, intent locks are doing what?
4. Talk about what is the leftmost match?
5. How to optimize slow queries?
6. mysql index Why is b + tree instead of b tree, red-black tree
7. How to select the sub-sub-sub-table library table key
8. In the case of sub-library sub-table, the query is generally how do sort?

This article ends, like a friend little bit of praise and attention, thanks! !