A closer look at non-blocking I/O in Node.js

Speaking of Node.js, you have probably heard a bunch of dizzying terms

About asynchronous, mainlyEvent loop and **Non-blocking I/O, **officially because of these two points, Node.js can be called high performance.

So it is very important to understand the asynchronous mechanism and usage of Node.js

What is the non-blocking I/O of Node.js

• I/O is Input/Output, the input and output of a system
• The difference between blocking I/O and non-blocking I/O lies in the time it takes for the system to receive input and then output. Can it Receiving other input

Example of queuing for rice

The difference between blocking I/O and non-blocking I/O It depends on the time it takes for the system to receive input and then output, and whether it can receive other inputs

• For customers/ordering staff
  Queuing up to order food is blocking I/O (customers at the back must wait for the customer in front to receive it before they can receive it)
  • Ordering food in the restaurant is non-blocking I/O (because there are many waiters in the restaurant, others order While serving, you can also order by yourself)
##Compare the canteen aunt and waiter to the software system

• The canteen aunt can only serve one portion Cooking on the floor -> Blocking I/O
  • The waiter can serve other guests after ordering -> Non-blocking I/O
Input = order food
Output = serve food
[Recommended learning: "

nodejs tutorial

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Examples of asking questions and waiting for solutions

For example: A developer raised a question on the forum: "How to solve this Node.js problem? Waiting online, urgent" .

The situation of blocking I/O is-> He keeps waiting for other people to answer, and when other people answer, he does other things.

The situation with non-blocking I/O is-> He goes to do other things, and then comes back to see the answer after a while

Example of doing housework

Xiaofang needs to do the following things to do housework:

Wash clothes in the washing machine (20 minutes))

• Sweep the floor (10 minutes)
• Tidy up Desk (10 minutes)
• Hanging clothes (10 minutes)
• Please design a clever and reasonable sequence so that Xiaofang can complete these things in the least amount of time

A: 20 minutes

• B: 25 minutes
• C: 30 minutes--because when the washing machine is washing clothes, Xiaofang can do other things✅
• D : 35 minutes

Understanding non-blocking I/O

Notes:

Confirm

system, enter, Output
• , what are they? During the I/O process, can other I/O be performed?

Understand the blocking I/O from the code

const glob = require("glob");

var result = null;
console.time("glob");
// 获取目下的文件和文件名
result = glob.sync(__dirname + "/**/*");
console.timeEnd("glob");
console.log(result);

Print the following results

You can see that it takes

30 milliseconds of waiting time

to get the result It can be concluded from the above code that

Blocking I/O has a waiting time, and no other things can be performed during the execution process

Understanding non-blocking I/O from the code

const glob = require("glob");

var result = null;
console.time("glob");
// 获取目下的文件和文件名
glob(__dirname + "/**/*", function (err, res) {
  result = res;
  console.log("got result");
});
console.timeEnd("glob");

console.log(1 + 1);

Print the following results

glob: 3.198ms
2
got result

It can be concluded from the above code that

non-blocking I/O reduces the waiting time , you can also perform other things during the execution process

For more programming-related knowledge, please visit:

Introduction to Programming

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