Epidemic faded interview on, five yards farming Interview Guide: + US group unfamiliar street Baidu + + + Jingdong Ali

Already more than 2:00 , it seems today is sleep, sleep anyway, write a diary summarize my recent interview experience it.

March 10, 2019 to handle the separation procedures, he left Vantone Center, and can be considered my second club officially said goodbye, but it is still very fond of International Trade,

This is a wonderful place to accommodate a lot of people have financial dreams often come here at night you will sigh empire night was beautiful, but unfortunately most people here are too busy to enjoy the scenery here,

Everyone lives under pressure, became a slave to money, but this is not a bad thing, because they have children or elderly parents, who bear the responsibility, it is also their only personally created a bustling CBD,

I finally chose to leave this place.

I have never denied my leave and about money, this is indeed one of the factors, I, like everyone else burdened with responsibility, so I need the money, but I want to say this is left for me to seek a bigger stage,

Make yourself more precipitation and rapid growth. I have tried to my leaders stated my values, I do not think money and ideals are mutually exclusive, can earn, the less valuable the more you work it, obviously it is not.

US Mission Network

 

The first vote is US group net, just listed last year, relatively rapid development, the US technology group is also one of the best in the country.

Filling in a material, and then the interview is

Algorithms and data structures as well as architectural design, the answer is very bad, many have forgotten.

First, realize his a hashMap, this beat me, jdk source of the most familiar with is the Collection package, using arrays and complete internal data structures like a hash table,

Then complete the insertion of the hash table query operation through the operation list and hash algorithm;

Second, the producer-consumer model code for concurrent programming, are left out, forgotten, and really should not be, oh, the easiest way is to use wait and notify to the blocking wake (basic stuff so I can forget),

Of course, there are many elegant wording, such as the use of reentrant lock (ReentrantLock), using a lock counter (CountdownLatch), etc. Then something did not think remorse;

Third, an algorithm title string, such a small case, is the bitmap method, there is no pressure to write;

IV., Wrote a familiar architecture diagram, so I put my system architecture of the old club moved up, in short, it will be called by hessian logic and back-end business logic decoupling foreground,

Maintainability entity may serialization and deserialization transfer (which is best at hessian dry matter), and ultimately improve the background traffic interface logic reusability of the system.

There twenty-three topic forget what it is. Time is very tight, only an hour. After an assignment start the interview, while continuing chatted jdk's Collection package,

There is the idea before the company made the deployment of the project. Two faces that talk java concurrent locking mechanism, why should this read-write locks instead of synchronized synchronization lock, understanding isolation of affairs,

Why dirty reads, repeatable read, read committed, etc., how spring of transaction management is achieved, programmatic how, aop style how to achieve, what is the principle of dynamic proxy,

Understanding the spread of the transaction. Such a word is more emphasis on the issue of principle, the answer can also be right, the last is the department head to direct the interview, talk about why departure, expected salary or something, also talk technical.

Q. I will not come, and finally I answered I think about next Wednesday to reply, and then left. Feel good corporate environment, what are the free drinks snacks to eat.

360

 

The second is to 360, there is no written examination, direct interviews, ask side of the main base, String content stored where, A runtime constant pool, and then I jvm memory structures talked about,

Heap, stack, program counter, methods zones, like the role of each area, then the question becomes, what jvm recovery mechanism is feeling a little big ask, do not know where to begin,

We had to start with the generational collection algorithm, and references from GC ROOTS chain mechanism to a new generation of small spaces and then copy algorithm Older Generation clear labeling algorithm, the last is the new generation and the old generation

And the relationship between transitions, etc., then the interviewer nodded his head and said that you then talk about class loading mechanism jvm it, it commissioned parents mechanism, is preparing to speak, the little brother asked how reflection

The use of class loading mechanism of it, had to implement the principles reflected also balalala. . . Continue to ask questions, to understand what design patterns, A: singleton, builder, observer, template method pattern,

Iterator pattern balala, you had to use in the project mode observer it, how to use. A: The unified configuration components used to make the time to publish subscribe zookeeper, creating listener list,

Complete application system registration and synchronization, balalala, while writing the code and telling details, is spoken vigorously, was interrupted, you write a singleton it, you think of a single case to achieve the most efficient to write,

Of course, is achieved through internal mechanisms jvm class singleton, and fast and safe, watching the interviewer nodded and said write one pair of check lazy singleton ... Ok obeyed, finished the little brother to ask questions,

Why use the volatile keyword, A: will appear at the abnormal high concurrency concurrent mode, you can prevent volatile instruction reordering, create an object operation is not an atomic operation,

Divided into three steps, balala, say a pass, the interviewer was persuaded, followed by the interviewer to ask questions, can talk about memory model thread, ha ha, but fortunately previous study thread visibility when studied this,

Finished interviewer is satisfied, feeling that he has been unable to hold me (secretly self-hi), talk about your understanding of the cas, A: I refer to the optimistic lock on it, and before I said, the interviewer said, okay, you wait a bit,

Interviewer came two faces, and asks, consider a scenario, the system needs a specific time in response to a user request, for example, the user request is completed within 100ms,

However, per unit time millions of users requests in peak time, that is, high concurrency, but I have to implement the system response in a timely manner, and highly available (no downtime), if you are an architect,

How do you architecture of the system and talk about your program, then listening to the brain Mongolia, and hate myself did not see that the "large-scale distributed site architecture" book, seat of your pants so he began to say,

First of cache clusters certainly needs to be done to prevent avalanches database, the database if the request also need a large amount of sub-library sub-table, all kinds of nonsense, to put himself dizzy, and finally the interviewer does not say some of the others,

But he did not say to the point, but you can understand, you work only four years of experience. Then he introduced me to what they are doing what the business sector, and then asked me why I leave and so on, to the point of the meal,

I was taken away. The next day hr call the offer, chatted salary, 360 good treatment, but also eat free, fine.

Street street

 

The third is unfamiliar street, I heard about a gun, ha ha ha, just curious social software, to see, side to write code, write deep traversal of a binary tree, a small case, recursive get,

Then ask memcache memory management mechanism, the answer: slab block management, the final chunk allocation, maintaining a two-way list of the LRU, balabala. . . Then he asked some of the stuff asked the zookeeper;

I asked the two faces of the more complex, most do not remember, actually asked vi command, I was kneeling.

Baidu

 

The fourth Baidu, Baidu this year is to stop the club trick, most departments do not only recruit community school recruit, but a few departments have special approval quota, then went to try one, side first came to write the code,

A single linked list algorithm topic, written, very satisfied with the interviewer nodded, then interviewer ask questions spring in your project is how to manage the zookeeper, A: balabala,

Zookeeper's leader selection algorithm to understand it, to talk about his process, you know zab algorithm, to talk about his process, sweat, asked questions are sick, I did not expect to ask so deep,

zab algorithm too complicated, zab is based paxos, and the algorithm paxos But Turing Award, barely saying a moment and said very guilty, there are a lot of blind spots themselves did not find out,

Fortunately, however, ask the interviewer nor down, but in fact I guess he may not be the (chuckle), then let me wait a bit; while the interviewer came after two faces, it is a mature uncle,

Two faces only asked two things, a jvm, a concurrent programming, jvm is mainly tuning, jstack use, full GC analysis and minor GC, etc., ask concurrent programming is very fine,

Question multiple threads to achieve the same status and then perform together, and then continue concurrent execution after reaching a certain state, how to achieve this, A: There is a CyclicBarrir after jdk5,

This is achieved by, it can be reused and so balabala said something, and then ask how to read and write after reading lock plus lock avoid writing thread starvation, A: feeding strategy balabala, ask how real

Now threads of control within a certain period of time to complete, it is not complete revocation A: implement Callable interface returns FutureTask Future class or interface, and then to trigger an undo.

I began to ask the project, describe the reconciliation system, balabala ... large amount of data it high concurrency do, how database design and so on, then let me wait for a while, but over a interviewer,

I asked the business, you pay a third party company, can not talk about paying technical processes, balabala ... his own understanding of the payment process talk a bit, and finally make a sentence,

Details of the business to pay is very complex, I did not fully understand it, sweat, so I waited a while, then the interviewer said you go back to other news, I think it finished, is it because business is unfamiliar brush,

Really can not be reconciled; sank a week, said on Monday the results hr Thursday called to let go one last time, is the technical director of the interview, Thursday Pidianpidian go

(Saying Baidu building too far away from the World Trade Center, had to take the subway every hour and a half, I was kneeling), all sides begin, ask questions idempotency asynchronous processing is not difficult,

Unique index or the development of a distributed lock chant, then turn immediately on the style, do not ask technical, and ask what you think of the value you bring to give Baidu Baidu,

You want your team to join Baidu is a what kind of team, how you communicate and product managers, and other R & D if you can not formulate a unified interface to how you solve, etc.,

Nothing prepared, stammered answer is very bad, hey, lost and forgotten!

Ali

 

The fifth plane is Ali, Baidu surface finish and other news, nothing else to view the company recruitment information, see Ali recruitment very attractive salary.

Haha, I was such a unchaste person, beginning with a phone interview, then the interview, and two faces on three sides, the main technical points have interview

JVM Related:

1. jvm in a full GC process (from ygc to fgc) what, will talk about how the object was promoted to the old era, several major jvm parameters
2. Do you know what kinds of garbage collectors, their advantages and disadvantages, highlight some of the lower cms
3. When there is a memory overflow, how do you debug
4. Knowledge JVM memory model to understand how much
5. Tell me what you know about a simple class loader
6. JAVA reflection mechanism

The internet:

1. What is the difference http1.0 and http1.1
2. TCP three-way handshake and four waving process, why the disconnect to 4 times, if only to shake hands twice, what will
3. TIME_WAIT and the difference CLOSE_WAIT
4. Tell me what you know several HTTP response code
5. Distributed architecture and design
6. How tomcat tuning various parameters of significance
7. Common caching policy which you used in the project what the caching system, how to design, Redis is used to pay attention to what, persistent way, memory settings, cluster, out strategies
8. How to prevent caching avalanche
9. How to do a distributed cluster unique serial number
10. Design a spike system for 30 minutes without payment will automatically close the transaction
11. How to do a distributed lock
12. What used MQ, how to use, and other mq compare what advantages and disadvantages, MQ connection it is thread-safe
13. How MQ system to ensure data is not lost
14. The principle of distributed transactions, how to use distributed transactions
15. What is the consistency of hash
16. Several HASH algorithm to talk about, you know, can be a simple
17. What is paxos algorithm
18. redis difference etc. and memory management of memcached

I gave back offer. But recently, 996 do not know how to choose.

to sum up

To write this, and write a bit more, can be considered to interview two weeks to make a summary, you may say, and wish yourself good luck, and hope are going to quit a job or programmer to have to see this article a little bit of help or harvest, I'll be satisfied.

Author welfare

Recently I am ready to face a lot of information but also read a lot of questions studied half a month, finishing the following detailed interview Zhenti tutorials and technical knowledge analysis, and now I have basically read, and now everyone will work together to enhance share.

Obtaining: background private letter reply to "interview" to obtain information portal.

 

 

Obtaining: background private letter reply "interview" to obtain information portal.