When is NodeJS Single-Threaded and when is it Multi-Threaded? 

😝 I refreshed my page 3 times.

Getting a play button from recoding videos from laptop webcam is very impressive.

Thanks for pinning this comment. I was about to restart my mac. :/

@@abhijiths148 kkkkk

i seriously started relaunched browser twice

Same

Same from my side as well

I restarted my phone twice 😂😂😂

@@bibekjoshi3522 i was also planning the same, but checked other video that was working fine, so i skipped my plan 🤣😂😂

after downloading i came back to youtube to confirm quality

🙏 glad it helped!

thanks for the clarification

Exactly , I was wondering for few seconds like did I learn the Javascript wrong since beginning 😂 then I realised by event loop he meant the main thread which is the v8 engine. Yeah event loop is the one which monitors the stack and passes on the callbacks

Thanks! I try to add graphics when I can its just consumes so much time and I only have an hour or two a day to make content.

@@hnasr no worries. I'm glad that you're enjoying your parenthood. 🤗

Interesting thanks , I have missed that in the doc “For the sake of completeness, we note that when you call one of these APIs from a callback on the Event Loop, the Event Loop pays some minor setup costs as it enters the Node.js C++ bindings for that API and submits a task to the Worker Pool. These costs are negligible compared to the overall cost of the task, which is why the Event Loop is offloading it. When submitting one of these tasks to the Worker Pool, Node.js provides a pointer to the corresponding C++ function in the Node.js C++ bindings.” nodejs.org/en/docs/guides/dont-block-the-event-loop/

Good question, I would love to follow this comment if youtube has a feature for it..

Good question.

There are actually so many ways, before that you need to answer what environment are you using docker-compose, docker-swarm or Kubernetes or running directly on a linux server. Major differences between cluster and worker 1. Cluster spawns multiple processes which may create memory issues but is great if you have a HTTP server sharing the same port ( Nodejs main process multiplexes it in the child processes) 2. Worker Threads will work on same process but spawn new threads, the threads share memory. This is great for CPU intensive tasks, file accessing. We use Worker Threads for Consumers in Pub-Sub Environment, where each thread may run a consumer. How to Scale: 1. Docker-compose,Docker-Swarm, Kubernetes :- For this I would recommend creating a single app instance without any threads or processes. Instead just create one app and scale it horizontally by spawning more containers. 2. Running on a Linux Server Directly :- i) For this I would recommend using Cluster or Worker Threads (Based on what task you are going to run eg: HTTP Server(Cluster), CPU Tasks(Worker Threads)) ii) I highly recommend using PM2 instead of Cluster as it will give you a nice way to get logs scale-in and scale out the app when running in cluster mode. If you have any suggestions or corrections please do let me know.

@@vrushabhgore8170 thanks for explaining things

You can use pm2 if your application is stateless

i thought my windows is working slow😂😂

does the main thread run inside event loop ?

I need to remember to turn off docker or get a new machine . My 2015 mac seems can’t handle obs

1. No. A non-master cluster doesn't have the fork function available to it. A script starts as the master cluster by default - i.e. master is created by the Node.js (we don't write code for it). This means that there can never be multiple masters. So - single master and clusters, that's it. 2. If you mean different Node.js processes, yes it'll work, since processes are isolated from each other.

the second connection didnt reach the main thread, it only reached the queue for the main thread

All promises/async await execute on the main thread including database queries from db clients, (unless specified otherwise by the client author) the database query is nothing but a network call which we established that it runs on the main thread. As a rule of thumb, if its not crypto, DNS, or io file read (directly to machine node is on) then it runs on the main thread. That being said If you used a third party npm package those might utilize threading so you need to read their doc. Stripe payment comes to mind Thanks, good question

thank you soo much 🤩, i was searching all over, its been really helpful 🙏

Eg We can say OSI first then tcp then http then tls I don't know if I get it right or not 😂

I just revised the order they look correct to me (beginners) start with osi , tcp, http, ..

if the file operations is asynchronous, it is handled concurrently as node delegates file operations to the os...not entirely sure how it does it

Yes, assuming cores are available. Otherwise these tasks will complete with each other.

Correct! They even say that in their doc

\b means go back one character, I used it another script to print the output next to each other. And copied it here where its not needed works as well..

1. Why - Node.js primary purpose is to run JS. File system ops are usually handled by the OS. To avoid blocking JS code execution, Node.js creates a separate thread for file ops. Using a single thread would have blocked the app. 2. I think #1 answers you're question.

Putting nodejs in a container and using cluster has no difference than placing it in a VM (well maybe if you put many containers are sidecars to the main node process but haven’t tested that) , In both cases there will be multiple processes. If you want to leverage the container orchestration you can spin up multiple containers each has a nodejs process and then use a reverse proxy / LB to distribute requests to those node containers.

There's no point in doing so, except if you have a weird requirement for very high security.

I am not so sure about Xmpp, but there are videos on http on this channel. There's probably one for xmpp too if you check

@@joshuaifara2736 True he did make on http, but I actually want him to discuss about some other popular protocols as well, that might be useful in different scenarios

@@navjot7397 Alright then

I did make videos on http here ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-0OrmKCB0UrQ.html And recently xmpp ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-OVN99SgBGkM.html

i think most of the places hussein was saying event loop was actually suppose to be the main thread, got me confused as well

Express uses http server behind the scenes so the same applies

Meet deno

Not quite, I would dare to say not actually. Network calls, file system tasks, DNS lookup, etc. are actually not handled by the main thread(NodeJs itself) and are instead written in C/C++, witch are themselves multithreaded(that's where libuv enters the show). JavaScript itself remains single-threaded. The issue of having a full JS code(without underlaying C/C++) witch is CPU intensive blocking your whole nodeJs instance persists. You will still have to work around it with things like worker_threads. That's just the way it is. As Alberto Gimeno points out on his blog on LogRocket, it is not a question of someone adding a new module in the NodeJs core and allow us to create and sync threads. If we add threads, then we are changing the nature of the language. We cannot just add threads as a new set of classes or functions available. We need to change the language. And change it without breaking it. I don't know, to be quite honest, if that's possible with JS, someone else may jump in and fill this gap for me, that would be great and add weight to the discussion. Let's take C# for instance, Java, and most versions of C++, they were designed with threads in mind from the get go, therefore they all have all of the facilities to handle them built in since their inceptions, not the case with JS. I remember while ago, like more than 10 years, a simple alert() in the browser was enough to block anything ajax you were doing in the background. It seems that all this time has passed and the 'single-thredeadness' is still there, still a single call stack, so it may be quite difficult to get rid of it without breaking some stuff. Relying on C/C++ bindings/wrappers taking advantages of libuv for everything you need to do in nodeJs is not sustainable on the long run. And finally I would just like to point out that I'm not a frond-end guy and my knowledge of JS is limited to the bare minimum I need to know. I gave up on frontends while ago and focused myself on the backend only. I've been just very curious about nodeJs for a few weeks and started learning about the technology before trying to learn the language itself.

@@jefersonnl You lengthy argument is useless except when you said "We cannot just add threads as a new set of classes or functions available. We need to change the language." And even here you didn't support this alleged "need" with any argument. So no, you can add threads without a problem and end up with performance that matches compiled languages. Side note: libuv was designed for Node only, then used by others. Another side note: the Majority of backend developers around the world are Node developers, and they are backend developers only. This means JS is a backend language with excellence, not a "quick fix" in the backend for those coming from frontend background.

​@@alithejumbo My bad if I went too technical or went down deep in low level stuff unnecessarily, with the risk of doing it again. What Gimeno meant with that was, we do not need to change the language, rather, a big change *would be needed* to make JS multithreaded, if one wished so. Since you seem to believe all the rest is useless, there's apparently no point in repeating what wasn't understood here. As Hussein always is point out to us, do not fall in love with a technology. Just understand what it is good for and what it is not good for. For instance, NodeJs will shine very bright in IO-intensive environments, no doubt about that, however it still has its shortcomings when CPU intensive jobs are regarded. And if you have a lot of CPU intensive jobs going on, and a lot of CPU cores to work with, you will need to take care of the complexity yourself with worker_threads and clusters, something other languages will just give to you out of the box, even PHP with the veteran HTTPd will give you that from the get go(though at the cost of several threads and processes and the dreaded context switchings). It's important to understand how things go under the hood, and sometimes take a look at what one's neighbor is doing, otherwise one can break one's heart when another language comes out with new features like virtual threads, fibers, transparent user space threads or light weighted threads like goroutines. All that we must avoid in the tech industry is to become close-minded and entrenched in our neck of the woods . This is why I started investigating NodeJs in the first place.

@@jefersonnl I went through your replies again to figure if I've missed anything . See, I write in Golang too, and I know how "better" than Node it is. But an easy Goroutine and Channel functionality doesn't outweigh the practicality and quick delivery of Node. At the end of the day 95% of the needs of any cloud server can be easily met with Node. So I won't nag much about the fact that Node's multithread-ability is on high level. It just works.

​@@alithejumbo Yes, everything seems to be centered around quick delivery nowadays. So Node will shine there. Also 95% of the needs of any cloud server (maybe not 95%, maybe a little less, but still above 80%), is centered around IO, "query this, give me back that, save this, delete that, retrieve that, put that on a queue, fetch that from so and so", and so on. Node will certainly shine quite bright in such environments as well. And when hiring separated frontend and backend developers could become expensive, having one programing language ruling them all becomes very attractive, especially in a startup environment. I can see when and where it works. How will we deal with some immaturities of JS? Only time will tell. PHP began as something very immature with a lot of issues and hacks, even so, it took the web by storm, and only them it mature into something like PHP 7/8.

ان شاء الله بحاول اتطرق لها في قناتي العربيه

@@hnasr ممكن لينك القناة من فضلك

true, haha.