TiktokI had an e-interview scheduled for last Thursday, and the questions were still a bit challenged, and the amount of coding was still pretty high.
one's whole face
One side of the overall very monotonous, about 50 minutes, the main two parts: the project and algorithmic questions, the project was introduced for 30 minutes, then the interviewer asked a few questions around the project, and finally brushed an algorithmic questionsum of the three numbers (math.).
second interview
The second face did not ask too much I now do middleware project, overall more than 50 minutes, guess may be a side has been asked, asked some of my bytes during the internship project, mainly to ask the amount of work, such as how long, the amount of code, how many pages of the design document this kind of.
Then asked about the performance tuning job on the resume, which focused on performance testing the middleware in the group and then figuring out how to improve network throughput.
me: Reduce the number of system calls by bulk network IO, change synchronization to asynchronous concurrency, remove some go-mysql duplicate operations
interviewer: I hear you talking about reducing the number of system calls to improve performance, where are the READ network system calls the most time consuming?
meThe system call involves a switch from the user state to the kernel state, and the contents of the user stack need to be copied to the kernel stack, which is a time-consuming process. The most time-consuming part of the process is the copying of data from the NIC to the kernel, and the copying of data from the kernel to the user in two passes, and in addition, if a process switch occurs, the TLB of the existing process will be invalidated, and the invalidation of the TLB will also cause a certain effect, but this effect is not so intuitive. Although x86 supports PCID technology, which can avoid TLB failure during process switching, this practice under multi-processor will result in the TLB entries of a process being spread across the TLBs of multiple processors, and inter-processor interrupts may be required to invalidate the TLBs of that process.
interviewerWhat do you know about TiKV?
me: At that time, when planning to do the binlog server, the study of TiKV protocol part, because the binlog server is very important point is the need to realize part of the function of the mysql master
interviewer: How does TiKV implement multi-line statement transactions? Has this part of the code been looked at?
me: No.
interviewer: Some conceptual questions: what is a transaction, MySQL transaction isolation levels, what is transaction consistency, what is strong consistency, weak consistency, final consistency. Understand CAP theory?
me: CAP theory content forgotten, everything else is ok.
There are a few more questions I've forgotten
Finally, an algorithmic question: bisection correlation, easy in mid
three-sided
Came up and asked a few things about Shopee Infra and asked me who the LEADER was, he said several people from our DATABASE group and seemed to know our group.
- You introduced yourself talking about networks, operating systems, do you know much about networks and operating systems?
- OS what modules have you looked at the source code for and how did you look at them
- How the kernel implements some of the commands for the file system in the operating system, such as iostat.
- Asked about the byte internship program, the workload and what I did.
- Ask me why I would want to go to Singapore when I love technology, after all...understand
- Ask me what I do in my spare time.
- Ask me if I know anything about CRDT.
- Asked me the overall architecture of the group middleware, and then the deployment method, after learning that it is a single-process approach, let me design a distributed system to unify the management of the cloud cloud, sort of a system design questions
- I was asked if I knew anything about TiDB, and I said I'd seen some of the code, debugged the
- I was then asked if I knew how Linux implements debugging.
- There were some other questions that I forgot, no algorithmic questions
state of affairs
HR interview appointment and waiting for HR interview.
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