How Node.js Works behind the Scene with Live Practical Examples!

Hello what's up guys, today in this video we will see what's behind the scene, yes guy, today's video is going to be very important because today finally you are going to know how to do that work behind the scene. Okay, so guys, first of all we need to understand the differences between synchronous vs asynchronous, so here you can see very clearly that I have just changed from simple to Keep only two definitions so that your doubt becomes clear and already we have seen this if you remember right so once we have this synchronous code over here and the other one is the synchronous then what is this synchronous and then asynchronous so you can see. Yes, any task that is executed sequentially is fine, any task that finishes the first one and then finishes the second one. Then the third one, then the fourth one is happening sequence wise here so they are known as synchronous task also they are known as blocking task also okay for example like we have a math operations okay if you pass any statement Or looping through arrays etc. Okay, so that is your synchronous code, you understood, many like, until the first one is completed, the second one will not start. The first one will not start until the second one is completed, the third one will not start, so each one has to wait till the end, okay, so here it is, guys, this task blocks the next one, I will just give you an example, don't worry but this is an example. Second What is a Synchronous Task Tasks Don't Block Executions It simply means they are known as the non blocking task for example when you Reading a file or when you are making a network request and setting a time out so basically this is an asynchronous task it is possible because of we use a call back promise and async await and already we have seen this so if you Want to Know More About Synchronous and Asynchronous and How They Works Okay so I would like to tell when we were working with FS module So here you can see here we have this FS module So here you can see what I wrote curd operations OK I wrote what curd operations and file renaming using synchronous version and then I have a I mean made a video regarding asynchronous Also, how can you perform the same curd operation but in an asynchronous way, so these two videos are very important please check out. Now I will highlight only these and tell you here and further there are more important things which I am going to tell you, so for example here you can see this is the code like we are requiring a FS module and then We have this one simple kasol dlog and even this kasol dlog is also known as your synchronous task and it is also known as your blocking task ok and Then again we have this particular code which is your it's not a synchronous it's as I mean it's not a sync it's a sync yes so this is a synchronous task of yours it means it will block your code so I control a save let's Run this code ok here I go and run so you can see what I am seeing is start right here you can see very clearly it is a start and then I am Getting my whatever is the console dialog by reading the file because this is the data if I show you so here we have this fact t once inside that there is this content so from this you have come to know one thing that it was both of the Your blocking task, this means that it will not run until it is completed, right, so now I do this, above, okay, I have done this, now let's see what happens, okay, now if I go here and enter. hits I see now that part has changed, some time back I was getting the start first, now the start is coming to me later because first the task of reading the file will be performed and till the time it is not finished you will have to This is not going to be visible So this is known as your synchronous task Also known as your blocking task which will block until the first one completes The second one is not going to run Now check it out that now how we know the asynchronous task So here we have an asynchronous task, okay, so let me comment, so we have already seen what I showed you just a little while ago, you know the sync version of the FS module, so one of the codes is this how. To read a file and then this is this one is how to read a file using asynchronous way simple no big deal ok then definitely check out the video if you are not a Remembering what is happening here, it is okay, so again I run it here and hit enter, okay, so now you can see very clearly here that the data is coming to me, it is coming evenly, okay but one thing. I do it right now, see, this was at the last, hence no problem, but if I put this part below it, then it is fine in this way, see, because according to the rule, this will go first, after that this one. That one should run then this one should run you are feeling right if it was synchronous but in between these two I have added an asynchronous task so now I have to see that first it will run no doubt but after that it will run Or it will run console dot log. Do you understand what is the work of synchronous? Brother, if it is taking some time, then whatever task is behind it, if it takes less time, then run it first. I am mine. when time I will come, I will leave. This fund of Synchronous is simple best. If it takes me one hour of Synchronous, then everyone will wait for one hour, even if there are tasks behind me which hardly take 5 seconds. Let's check it out. What is it? I am here. I also make this a clear run so you can see very clearly and this is the beauty of your asynchronous task that this is running at the last right whereas I have run this at second number. It was written and look at the start, it got run before that, so this is how it works synchronously, it never stops anyone, now it does one thing at a time, now I take it to the top, okay, where first it is in its place. Then we have this particular a synchronous right at the end so let's check it out now what happens so guy now it's your chance you guess what will happen like first of all I will get start this code will run or This code will run, basically tell me the sequence, will it be 1 2 3 4 or 1 2 4 3 or 1 2 3 4, in which way it is going to run. Let me know in the comment section and for now, just pause and try. Do it okay I hope you have tried so let's check it out what happens is I run here and boom guys see now you can see very clear and that This is how it works Start came first No Doubt and Aana was to come, after that this file of yours which we read in a synchronous manner No Doubt and Aana was also to come but in the third part ours was this This is basically this particular code of asynchronous but this is the Beauty said, brother, it is taking some time, you can run whatever code is below me, it is so Ts and here you can see thumbs up and here you can see thumbs down. Okay, so now let's check it more and I think this will be one of the best PPT and one of the important PPT for new developers because till now this doubt is not clear in your mind that how is it doing asynchronous. Everybody is like there is only a single thread in the nut which is fine so you can see here we have this v8 engine so guys what is its main function what is its main function To convert your JavaScript code into machine code for high performance, simple, you have to say itna and it handles the synchronous task, yes guys, this is the v8 engine, it handles your synchronous task, for example, a basic computation, you say, or variable assignment, you say. Take or any such execution which is happening line by line then v8 engine handles your synchronous task but here is The main library here is the main package because of which note just can handle a synchronous operation and that is your leave Yvi library so you can see very clearly what this is is a C library it means that when you You work on React, so React is not a framework, it is a library and whose library is it? React is a JavaScript library, in the same way it is also Livu which is similar. Language we have given C as c+, if we read it in this way then C library is what I mean is C's library is leave UV that provides note that with cross platform support for asynchronous operations and now you understand that as soon as we say asynchronous, we have a file system to read. There is networking and much more and the best thing is guys it leaves UV right it includes your even thread it is very important And your thread pool enabling non blocking task like file reading networking and timer this is it so guys nut in which asynchronous task is possible because of this particular library and this is your event loop right here you can see this is your Event loop and thread pool is being provided and because of this only this asynchronous task of yours is possible in your existing application so I hope. Guys now you know so we have a v8 for your synchronous task and then we have this leave uv for your simple asynchronous task okay so for synchronous this is for asynchronous we have this particular library of C then now this one Of the important is and and in tomorrow's video I will come to another and in depth a PPT like final on how not just work but this It is important, so see, now you can see very clearly, we have one particular main thread, we have a main thread, right where you can see, we have, just the first task of this main thread is to initiate, that is, the program and its simple. It means that this is the part where you are not just beginning executing the program then we have this top label code top level code, you understand like this, any such code which is Outside your function like declaring a variable or running a basic command, so that is, any such library or any such file in which your program or your application is dependent, you come to this particular part. When it loads, then you understand how one by one step by step and the work is being done here. Pay and then finally we have this register events call back. So you understand that its work is to Set a Function that Will Run When Certain Event Occurs Like Reading a File or Handling a Request Alright guys now finally we have come to our main mechanism note whose end is called your event loop even in JavaScript also we had read this event loop right so Its main job is to keep our program running successfully and handle whatever task is assigned to it. Now we have something. Called off loading and then we have something called thread pool now here this is the thread pool by default it has four threads first second third and then fourth so by default it has four threads which is who is providing it note that obviously your This leave UV library is providing, now let me tell you what happens, see and what is this uploading, I will also tell you now, so the first thing that happens is that Whatever lightweight task or synchronous task you have, it will be handled by your main thread. For example, understand that your v8 engine will handle it, but when it comes to your heavy weight like your heavy tasks like system operation. I mean, call it file system operations or encryption part or compression, all these things which our main thread is not able to do properly. This is also a heavy weight task, you assign it to our thread pool, now it will be here that one by one it will handle those tasks in the thread pool and it will make sure that your system is running properly in the background. Keep going and end which enables your asynchronous operation. Do you understand guys, what is happening here, all the small things will be handled by the main thread and all the heavy weight ones will be handled by you. The task is fine like file system, I told you cryptography, compression and all two things happen is that it is uploaded from the main thread, on thread pull and here what is done to them one by one, guys it is performed and Once it's done it is sent back to our event loop you know and there it gets executed so this is how your note just works behind the scene where we have a google2 loop That's also a part of your leave UV. Do it's leave in your main thread and thread pull is a little separate so ya guys this is it, that's all for this video today and I really hope you liked the video very much. And finally these three slides would have given you an idea of what is sink versus a sink and then you are this particular note whose elements are two to two and then at the end we have this nut. How is the program basically starting and how is it executing all the work one by one so ya guys this is it, that's all for this video today and I really would have liked the video very much one more time this is synchronous How can you do a card operation in a synchronous mode? Please check it out. So guys, if you like the video then please like it. Share it with your friends and if you have any doubt. Let me know in the comment section so guys our next target is 8 lakh subscribers if you haven't subscribed yet then please do so I will meet you in the next video till then guys thank you so much take care [music]