New Course - Node Internals and Architecture

Key Takeaways

what's going on guys my name is Hussein and I subscribe to the belief that understanding uh a technology allows us to build better software on top of it and I believe the least understandable technology that and yet the most popular one is is no JS as a runtime so I spent seven months or so the better part of 2024 and 2025 uh just delving into the internals and architecture of nodejs and I found so much Beauty there so I designed this particular course that I titled nodejs internals and architecture to help the engineer look with nodejs with a different perspective in a completely transparent way to write code on top of nodejs and be able to tell exactly what happens behind the scene have you ever run nodejs code and you run it once and it produce an output and you run it again and it produce a different output that is absolutely explainable you can explain why it happens but only when you understand the different phases of the event loop I designed this course to be three major sections the first section is the node architecture what is this V8 engine why do we need it what how does it work what is the optimizations it does compile and to interpret to be specific this the JavaScript into executable code what happens what is the difference between interpreted code and language and compile language what is really the the major difference here so we talk about that talk about V8 in this architecture another component another part of the architecture is the this beautiful Library that's called libuv which is responsible for pretty much anything I owe in njs what is it what are the threadpool that exist in it how does networking Works in this Li in this Library how do we do IO and the major component of this is literally the event Loop what is this event Loop in njz what are the different phases I have a lecture for every single phase because each phase technically deserve its own lecture you know at 30 minutes or so just discussing how an input from one phase goes to the another phase and how do these are linked and why do sometimes when I run something I get the output or flipped all of this can be explainable once we understand it node packages how do node packages modules what is the cost of importing a module what really happens behind the scene understand that just calling Fitch or sorry require module or import module what's the difference what really happens behind the scene and and again you might not be interested and that's fine and again I'm talking about those who who look at this piece of technology and want to kind of explore what's behind and that that's pretty much all my courses are like that and even when you consider taking this course you'll see me just enjoying the process of exploring what's behind the scene and it's so amazing how much stuff what is promises what's a promise really in no JS and and we watch we're going to we're going to watch How to we distill that that you know abstraction down to its basic component it's so beautiful the package managers how do we link together so that's the architecture section then we take a magnifier glass for the second section node internals now let's go deeper in every single major component in note how does node TCP Works how does node DNS work what are the internals of node HTTP what are the internals of node https and I'm now let's link every single thing we learned in the previous architecture right here now show me what happen when I when I receive a request from the client as a server as a njs server what phase get executed is it the poll phase is it the check phase now what kind of phase does the request get executed in and why do we care even well we care because any delay in any of these phases because of code you have inserted will delay the next phase and when you delay the next phase you are potentially blocking the main the the the the event Loop and when you block the event Loop you delay a potential i o to the network which thens getting felt by the client or the server right depends who where are you looking from it's absolutely amazing looking at just taking the lib UV library and then breaking the thread pole and understanding how it does no DNS why when I listen on a port without a host name I can connect immediately but when I listen with the port and a host name the the listening gets delayed I cannot connect immediately it takes me a while what's the difference there is no magic it's just pure understanding of how DNS linked to socket management linked to how the kernel behave and it's all explainable and it feels so good when you understand these kind of things so I dive into lot lots of stuff here I'm looking at the lectures here it's beautiful we talk about node HTTP https UDP uh uh node streams which is a completely new abstraction in node that sits on top of pretty much almost everything that we use in node like a request in the client is what was called a writable stream because it's can continue right you can continue to write a request and it take a while because let's say you're uploading a file uh uh while a request on the server side is actually a readable stream you know because you keep reading stuff processes thread how do you clusters how to do socket Management in nodejs with the cluster module such that you can distribute connections that is that are incoming to nodejs between the different processes what are the different scheduling policies what are the difference uh what's the difference between them what is the most optimal what is the limitation currently and finally after having complete and deep understanding of the architecture the internals and the different components we bring it to the final section the performance and optimization Ts for nodejs and these are best practices that are in the wild and take best practices always with a grain of salt whatever is best practice today may be not in the future but any best practice anything that we say in this in this particular section I try to link it to a why you will always find it that anything that we mention this is why callbacks are constant because they may block the main Loop and if the main Loop what what's the what's the problem with blocking the main Loop well if you block the main Loop then you will delay the poll phase where what's the problem with delaying the poll phase then the io will be delayed what's the problem with delaying the io well you're not going to read from files you're not going to write to files and if you don't write to files you might cause corruption because someone accepted something expected something to be written and it's not written yet because you delayed it or an IO might be sent and it was not sent like a request like you're writing to a socket and it was not sent back to the client or back to the server because of a delay that happens in the loop so how how can I get around it well we can schedule it there's so many tips here we can partition we can partition the expensive compute we can offload it to complete thread we can offload it to a completely different process heck we can do a C++ add-ons in Nos and I'll show how to do that we will if if if the function is so expensive to be written in JavaScript we'll write it in C++ and we'll compile it and we'll link it back to no and we'll run it and I'll show you even how to debug C++ code from JavaScript is so amazing how much you can do with this stuff I I had so much fun designing this course and I hope you enjoy it give it a shot go to node. husin n.com for a discount coupon and I hope I see you there thank you so much for all the support appreciate you guys see you in the next one