How Node.js Works: V8 Engine, Event Loop, and Worker Threads Explained!

Hello what's up guys today in this video we will see and nut juice application box yes guy today's video is very important but before that don't check out the other previous videos and even yesterday's video behind the scene please also. If you definitely check it out, you can see that everything is visible to you in a graph here, how your note works as it is, so you can see it very clearly. First of all, here we have an application. Okay, basically this application, you understand that with Let's you are coding in JavaScript, okay and with Let's you are making a simple to do app. Which page guys to do? The app is simple, so when you create this to-do app, what kind of code do you write? You obviously write the code in JavaScript. Right now, tell me one thing in JavaScript that you use in console dialog or anything. Document: Gut element by ID, your computer may not understand it, right, your computer will not understand it obviously, so now what happens is that the JavaScript code goes into your v8 engine and basically what is v8? An engine is for example, your car or even your bike, the more powerful the CC, the more powerful the engine is and the better it is. Right, then you should understand that V8 is such an engine which Obviously Google's crypt converts it into your machine code, so now your system will be able to understand what you have written. Alright guys, now guys, after that comes what is your nut code binding? First what is this binding, what is the meaning of this binding? See guys, the main function of binding is to connect your JavaScript in to your underlined system. Now that system is something. It may also be possible that whatever your operating system is, it does it fine, but now you have to request the operating system that I want to read the data of some files or I want to make some network calls. Okay or I have some process which has to be performed or run, now that guy cannot do your B.Ed, it is obviously related to your operating system right or say it is related to your server, then there is this Binding is it will make sure that your JavaScript gets connected to your system so that both of them can communicate with each other and here by JavaScript I mean your nut JS. Have a node just now. Now this binding makes sure that the node can now communicate with your operating system, whether it is requesting a file or If you have to make a network request or perform some process, then you can perform those operations very easily with the help of this OS. Okay, now after that, this is very important here because the task keeps coming one by one and so on. With the help of this leave ub library which I told you about yesterday also which was created with the help of your c so it's your c library which they named leave uv and because Off this library only note: Now guys, now your can perform synchronous operations very easily. Now guys, understand that you have made a request to your operating system or server that I want to read a file, what to do is read. It is okay to do it and I have come till now, now how to read it asynchronously? And let's imagine, you have asked me to read a lot of files, so now everything will be read at once, otherwise, what will happen now? The part which is the note, what the binding will do, the whole task which is one by one in the event queue, one by one, 3 for four, in this way, one by one, it will go into the queue. Obviously you must have seen the queue, even you have also heard in the data structure when If we are somewhere outside in a school, we are engaged in the queue one after the other in height wise, no first come first or kind of, then in the same way, all the tasks which are asynchronous heavy weight tasks are one in your event queue. Buy one now guys that is stored there now now here whatever is most important which is your heart aapke note jas ka jo heart hai and that is your event loop so what is the function of event loop the function of event loop is that Of all the tasks in your event, is there any one left that I have to process? Then it keeps checking the event loop continuously. And the two most important tasks of the event loop are that Check whether the task is a blocking task and a non-blocking task. If it is a non-blocking task, then do a simple call back from lets, then it gets executed immediately here itself, will pass it here, will go from here to here and then return to you BA. And then you will get it in your application, so in this way that communication will keep happening but let's guys that now your a blocking operation is a blocking task right like here with file systems something Be it any work or some network related work or some process related work, the event loop does not execute it immediately but you are able to see it. This is your worker thread here, what does it do, if it passes it, then now here is the worker thread. Will do its work and one by one it performs all the tasks and and once that task is completed then guy we have this execute call back here you can see very clearly basically now What happens here is that once the work is completed then the worker thread will place the callback function in the event queue. Okay and now what that event queue does is that this callback function can easily handle it. If he takes it, he executes it and returns it back. Here, from here, you go directly to pay here and then simple guys go here to pay you with the lets that was in your application that brother, let me read the file. That data has reached here, you will see it in the console or wherever you wanted to show it, so guys, this is how your application works, I hope you have understood, this is a quick recap, I am quick. Let me give you a recap, it is simple, no big deal, okay look, first of all you write your code in JavaScript, from Let's you have to read a file, okay which can be in your server or somewhere in your operating system. maybe then it will happen First of all, the code you have written must be written in JavaScript. Now understand that if we talk about the note itself, I am telling it with the help of JavaScript. It is okay, if that code does not understand your system then v8 JavaScript engine which converts your JavaScript code into machine code so that your system can understand it. Now the system has understood that it has to read this particular file, so now what will happen is that this particular nut This is the binding of Jas Basically, the binding that you see here will make sure that your JavaScript, which is basically your operating system, gets connected to it and once it gets connected, then obviously it will now be able to access the files and data here. Content is everything isn't it and after that all the guys will be your task and where will they go, first of all they will go to your event queue one by one, okay here they will go one by one and after that the guys will now go to your event queue. What is most important is the event loop, that is the heart of the node, where it makes sure that there is some task left in the event queue that I need to get to its right place, if it is as simple as a call back, a simple call. If it is back type, it will execute itself and it will return. You understand, it will execute itself, it will return this here, it will return this from here, and it will return this from here. And whatever you wanted, you will get it on the system but if there are some blocking operations like dealing with file system or something involving network calls or processes then what happens are they are known as blocking operations and note in which sync should run continuously. Operations Right So what does the event loop do? Pass it on to the worker threats. Now what does the worker threats do? It will do its work. Simple, whatever task is given to it, one by one. Will complete then again in the form of call back will return the event loop here, so it will obviously execute it very easily, then return from the same, return it from here, return it from here, return it from here, and in your application, you have It was written that I have to read this file, show me its data, then you can see your data in this manner, so ya guys, this is it, that's all I hope for this video today, I liked the video very much. I will share it in PPT and the rest of the previous video and even yesterday's video was very important, definitely check it out, so guys, please like the video if you like it, share it with your friends and our next target is 8 lakhs. Subscriber, if you have not subscribed yet then please do so, I will meet you in the next video till then guys, thank you so much take care. [music]