I had ape in the face counseling, where to go, open view, street street, headlines, Ali, deft, the US group, after Tencent, in addition to harvest a lot of interview questions, but also to think how to be the interviewer in the eyes of "love technology and love think, tricky, potential candidates "some" routine. "
Interview Questions (Java back-end)
Ape counseling
1. The eight queens problem
2. The binary tree of the longest distance (any two nodes longest path)
to achieve 3.lru Algorithm
4. a data structure designed to meet the two methods and put getMedium (median).
(time complexity analysis, getMedium in constant, n, log n time complexity of how to achieve return)
5.rabbitmq split brain problem, rabbitmq delay queue implementation, rabbitmq high availability strategy
(as used in the project and their technology selection appears rabbitmq overlap, asked this question)
- Sike details of the project including the following:
there is no comparison when design a variety of programs, why choose this program?
You personally the most rewarding and most challenging work which one? - Java Architecture / Distributed: 705 127 209 (Daniel exchange group) no development experience do not add!
Thinking:
- Ape counseling ask questions algorithms belong leetcode easy, medium level, basic is not too difficult
Kuang view (Python)
- How Python multi-threaded / multi-process programming
- What Python GIL lock is? Why is there GIL
- python coroutine have used it have? What are the common coroutine library, tell us about
- How python decorators to achieve, the principle of common usage scenarios?
- I did not hear a bunch of python libraries, have not been used. (I did not write it down)
- Linux give you a path, the path seeking the simplest, for example, (/ a / b / .. -> / a, a / b /./ -.> A / b and the like)
- Give you a 16-core, 32G machines, a large distributed storage unlimited space. 16P text file size of a sort.
File one record per line, separated by spaces such as
key1
key2 - Tell us about what is external sorting
- Java Architecture / Distributed: 705 127 209 (Daniel exchange group) no development experience do not add!
Thinking:
- Kuang view of the interviewer and I Sike python. A little project experience did not ask.
- In addition to leetcode also see more high concurrency and large data related to system design problems.
Where (Java)
- Why MQ, MQ how selection, how to ensure the reliability of information, such as how to ensure power
- Used dubbo it? Rpc design a framework.
- Introduce https
- Database thread pool, http connection pool has not seen the depth of source? Tell us. (The project was used to get the http client)
- Give you one billion data, the quickest way to add to the database
- Distributed lock technology selection, implementation principle, comparative advantages and disadvantages, zookeeper principle of coherence protocol
- Several differences java thread synchronization, countdownlatch and fence
- How to implement synchronized and reentrant lock aqs
Street street
1. Distributed Lock implementations compared Why zookeeper, zookeeper coherence protocol principle
2. Hash consistency principle, achieve, how the project is to use consistency Hash, the introduction of a number of virtual nodes?
3.java the synchronized and AQS the principle difference
- redis ordered list
- What redis highly available architecture? Difference codis and redis cluster fragmentation
- How to print two threads alternately 0-99
Headline (Go)
- Linux give you a path, the path seeking the simplest, for example, (/ a / b / .. -> / a, a / b /./ -.> A / b and the like) and asked Kuang view heavy
- top-k
- Achieve prefix tree
- Python decorator achieve implemented method, and classes implemented with the parameters, and with no arguments. Consideration of the decorator and
- How to achieve multi-room, multi-chassis network before health monitoring.
- How to understand the process context switch, the process address space, why the process address space, system calls implementation principle, top command description.
Ali
- mq message reliability, such as how to ensure power
- Distributed Lock implementations compared Why zookeeper, zookeeper consistency principle agreement
- Thread pool parameters, blocking queue implementation.
- Hash consistency to solve a problem, how to achieve? The role of virtual nodes?
- Lock Java implementations, compare? AQS implement the principle of? Fair and unfair implementation principle?
- CAS implementation principle
- volatile implementation principle, singleton
- java memory model, gc tuning experience. cms gc several stages, why would stop the world appear. What are the common parameters can be optimized.
Why do we need to optimize gc, gc will cause any problems. - mysql transaction isolation level. mvcc implementation principle
- mysql indexing works. Why use B + tree index can not be used and when?
- mysql architecture, engine and server layers each layer is responsible for what.
- hashmap implementation principle and concurrenthashmap
- Spring aop principle, how to define a new spring xml tag
- Merge two ordered lists
- How to design a large-scale activities of the security system (open questions)
- You usually have to learn in what forum?
- How to learn an unknown technology?
- Java Architecture / Distributed: 705 127 209 (Daniel exchange group) no development experience do not add!
Thinking:
Although the algorithm does not face the interviewer Ali, but the interview comprehensive study points to combat, from simple to complex processes, grabbed hold until you will not be far.
Harvest most of the interview, the interview also feel their own gaps.
quick worker
- Thread pool implementation principles, how to tune
- How to achieve a delay queue
- mysql index
- mysql transaction isolation level
- java lock and common thread synchronization mode
- zookeeper distributed implementation and the pros and cons, how to avoid multiple clients simultaneously acquire the lock?
- Seek common node binary tree of two nodes
- Binary tree depth (non-recursive)
- and a set of common principles java class
- tcc principle
- netty request processing flow. threading model
Yoshi团
- The principle of HashMap? Expansion principle? Why jdk 8 modify the insertion position of conflict list
- mysql high availability architecture. master-slave synchronization process.
- the difference between http and rpc call
- How redis single-threaded support high concurrency, redis common usage scenarios
- How mq selection. Why mq
- Hash consistency principle
- US group pay takeaway cancellation request unpaid within 15 minutes. How to achieve
- Print * asterisk isosceles triangle
- The whole project link architecture, there is no single point and solve the problem which common single-point program has.
- What metrics can measure the output of the project work there.
- How to say what you are responsible for the most complex, the largest number of participants, for a long period. The project is to promote the
- Where do you think your strengths, weaknesses in.
- Your career planning for the future, you expect the job content, what is the direction?
- Java Architecture / Distributed: 705 127 209 (Daniel exchange group) no development experience do not add!
Tencent (Java)
1. How to get in physical and container cpu audit, how to set the number of threads, how active trigger GC
2. The role of consistency Hash, Hash, and why is it called consistency Hash, consistency is reflected in where.
HashMap can also use What manner Hash conflict
3. thread pool parameters, optimization, principle
4. implement a function:
CAT /usr/local/*.log|grep tencent
1. concurrent IO
within 2. 30 s must return results
- How to understand the Future mode? The principle of java
- Java blocking queue implementation principle
- Lock volatile java implementation principle
- mysql indexing works, transaction isolation level, which will be mysql deadlock scenario, how to detect internal deadlock?
- java thread synchronization total of what kinds of tools?
- Do you think java designed to be relatively good place to what?
- How to understand object-oriented design, you can get open source code or read the actual project tell us about it?
- Principle java class loader and actual usage scenarios.
- java memory model, the virtual machine default stack size.
- Talk about common solution ideas highly available architecture
- Java Architecture / Distributed: 705 127 209 (Daniel exchange group) no development experience do not add!
Thinking:
Tencent side of the interviewer is very in-depth investigation, require you to have the ability to generalize. For example a distributed load common strategy,
a common scheme distributed synchronize data backup. Several thread synchronization and so on.
And after that you can continue to answer further pressed.
unlike other interviewers thrown out, he hears you blow. you can blow much, how much you think he will.
Think
- Shredded algorithms need to be prepared to ensure that 100 questions before the interview brush enough, and some design problems.
- Whether will not, must not panic, whether it will, and the interviewer must confirm their understanding is not correct, how this question should be thinking about? Avoid deviation
- Interview focused on communication.
3.1 Conclusion forced summary
Be sure to communicate with the interviewer and methodical nature. Avoid the East a broom, a broom West. The best think well in advance some conclusions, repeated several times so the interviewer may directly use your "conclusion" to write an interview after the conclusion and evaluation. Then one thing, the best organized of conclusion, let the interviewer was impressed. even if forced to draw conclusions focus 1,2,3 stronger than an abrupt end.
3.2 The elegant interrupt the current problem, just quit discussed at checkpoints, in response to the interviewer interrupted
When the interviewer appeared in doubt, throw the problem, interrupt your answer, must not blindly answer, respond immediately grasp their own pace, before the interviewer comments, can finish the rest of the continued rapid says finished, remember to summarize the conclusions seek common ground, to avoid controversy.
Your interviewer is not familiar with your project, your history, speaking, listening, discussion three stages there will be a loss of communication information. Clear to the interviewer, let him understand, may be difficult to agree with you. But if the controversy appears, .. will reduce your favor, reduce the efficiency of communication so you are responsible for the timely termination of the debate about the techniques you can use:
- He reiterated that context, purpose, status, background, pros and cons of a choice.
- Frank recognition of this our design, implementation is not perfect. Even doing a good job. We have presented what optimization points (proposed solutions).
But not very high priority (priority is the best rejection pan mode). Since the original focus more on business objectives. Forward-looking technology has not done enough. your opinion really sharply,
this problem let us headache for a long time. - "This is indeed complex, we summarize, refine it and then discuss their differences," the interviewer generally will not refuse, the initiative to regain control of the direction of the interview to you. (Have a sense of initiative)
- Differences in the refinement process, in fact, reach a consensus, some of the minutiae of the debate, and the interviewer to explain directly, you can ignore the consensus laid out to you and say:..
"Our differences are mainly what, in fact, I each clear, explain for the interviewer questions about, or thrown pot, we want to optimize, because priority and we want to do,
but because not enough time, or the time XXX, did not. but then we do eat the loss, regarded as technical debt. "
(no problem to admit low, the strengths of the loading force is the most unyielding hundred and fifty)
Interview three thousand asked
Resume important to you? Just write okay
Resume must be carefully written. Interviewer throws, in addition to the common high-frequency interview questions, that is what you wrote in your resume. To ensure things resume writing,
a thorough understanding! Whether writing is to understand, or are proficient to master. otherwise, do not write
my opinion do not write
1. unfamiliar, just aware.
2. in the whole school thing, lacks visibility not write a
3.github have, but I have not been asked github the project
Project experience ask?
Project experience is generally the interview will ask, ask of focus. So the first step to give priority to explore the highlights of their own projects, to do their own work clearly written.
Self-introduction phase the focus should also introduce their own project experience, then best prepare yourself ahead of a speech to highlight his project say it.
more practice a few times. but to avoid the brain, the Yellow River burst its banks type answer, think of where to say where.
Common high-frequency problem?
java lock, thread synchronization, Juc package. thread pool
memory model, gc tuning
mysql index, locks, transaction isolation level.
Common distributed high-availability architecture redis, mysql, zk, mq etc. data synchronization and data partitioning, data backup Wait
Questions need to brush it?
Ali algorithm generally do not ask too many questions.
But at least half of the company will Shredded algorithm. The various types of brush leetcode questions are more than ten basic no big problem. Hard questions generally do not ask.
If they interview performance is very good but because the algorithm is brushed off the question is not will regret it?
algorithm can be extended question a person's thinking, it is useful also exercise a person coding capability. personal recommendation algorithm whiteboard with python is very simple. more focused problem-solving ideas
If they are particularly good performance in the interview, job matching is very high. Algorithm problem is waterproof, it will pick a simple question to ask. The purpose is to leave you, afraid you could not answer, to avoid embarrassment
But the relatively poor own interview, answer questions algorithm particularly well, it will not reverse the results of the interview? Basic will not, Shredded algorithm is only an auxiliary project experience and fundamentals are the core questions.
Interview results can ask?
If there is no interview to hr, or eventually face the interviewer does not explicitly hr will contact, I basically would ask. Or ask your own shortcomings. Usually tell myself.
In addition, Shredded algorithm OK, will be washed off. I was in street Shredded street algorithm is perfect, the result was hung up.
Generally rounds of interviews?
Not hr, are basically three. But if the two began to pull imaginary interviewer, and introduce you to the project, ask your career path is probably two faces end face is not clear to ask the interviewer.
Usually work the water, interview cramming okay?
Not work
When the interviewer pressed the details of the project, if usually not particularly familiar with the details, doing so-so, not enough technical depth, such as why do technology selection, other programs? What advantages and disadvantages of that?
Without research, the interview will soon eluded capture.
If the overall architecture of the project are not familiar, familiar only with their own modules, also may be associated with the module to the interviewer asked, if they are not familiar with the project, will soon hesitated. If you answer, this is not my responsibility , I'm not familiar with, it will make the interviewer did not produce the bigger picture for you, not enough sense of initiative suspicion. assessment will be "only to complete the work within their own module evaluation, the system does not understand the global, not strong sense of initiative self-awareness drive poor "
Work may focus only business, for lack of a project application technology concerns the interview when the interviewer will be caught. If I had not thinking clearly, and do not realize that this piece of technology risk before the interview, it will bring to the interview great risk. US Mission interviewer once asked me, you party up to introduce a major responsibility, the longest cycle, how the most complicated of a project to promote? If you usually do not work actively, not active thinking, the interview is so stalls one problem basically speechless. (I was stunned)
Just look at the blog, get to know the high-frequency face questions okay? (Problem-driven preparing for interviews)
This is a must do. But just do not be enough
E.g:
Ali interviewer asks: gc Why must stop the world in general blog did not give a clear and precise and intuitive reason?.
How to achieve consistency Hash? Shredded it. Why is it called consistency hash, consistency is reflected in where? No general blog.
lru algorithm Shredded look. blog there, you can read through the Shredded?
How redis and zk distributed locks for selection? Their shortcomings, the advantages? How to avoid the disadvantages of the negative effects of the project when using?
How Fairness Unfair and AQS achieve access to the lock?
The interviewer even give you gravesites, said a deliberately wrong, see if you can refute.
Pit had been brought before me, the thread pool problems
interviewer asks: is first come first added to the max size or blocking queue?
I say blocking queue is full will continue to create a thread to the max size
interviewer:? Is it true that if it is Would not it be unbounded queue never reach max size
I thought to myself: Yes, ah, makes sense, then I may remember the interviewer with a migraine.
So the conclusion is that the optical read down, not enough to deep understanding. Time with questions to learn problem-driven learning.
Finally, you will find,
After a long time, you still own the most impressive had put forward ideas and answer questions about their solutions.