DEV Community

Everything you need to know about Node.js

Jorge Ramón on July 05, 2019

Node.js is one of the most popular technologies nowadays to build scalable and efficent REST API's. It is also used to build hybrid mobile applicat...

Read full post

Mohamed Hussain • Jul 9 '19

Thanks for this clear article on how the things are done in background using nodejs....I have some question : what is the difference between worker threads and os threads....in prime number example why os threads are not used by default by libuv when doing CPU heavy task...what is the limit for the os threads...

Pierre Lebrun • Jul 10 '19

As said in the article, your code must be written in C++ in order to be able to use the OS threads pool.

Hence the introduction of worker threads which can be used directly in JS.

Jorge Ramón • Jul 11 '19

Yeah, he is right :D.

That's why DB drivers are written in C++.

Eugene Karataev • Jul 6 '19

Thanks for the great post!

Let's say I need a worker to do heavy CPU calculations. How does the worker works under the hood? Does it start on a separate CPU core and uses this core by 100%?
What if a CPU has only one core? Will Node worker help with this case or it'll be useless to start a worker, because there are no free resources to split between the main thread and worker thread?

Jorge Ramón • Jul 6 '19

Thanks for commenting.

Node.js by default works in a single CPU core, so worker thread will spawn and execute in the same CPU core that the main thread does.

If you want to deploy a Node.js application across all CPU cores you need to write some code using cluster native module. Thanksfully there is a library called PM2 which does the dirty work for you and deploys a Node.js application in all CPU cores with its built in load balancer.

The worker thread real problem is spawn like crazy, since creating a subthread (worker thread) isn't cheap (talking about CPU time and resources) but it's cheaper than fork the same process.

Eugene Karataev • Jul 6 '19

Well, if a separate worker and main thread are executed in one CPU core, then they share the same resource.
Is it correct that if we write heavy CPU code in "chunks", i.e. we will return execution context from a heavy function to the function which handles http requests with some interval, then we will emulate workers? But in this case it's not necessary for Node to allocate resources for a subthread, i.e. it's cheaper in terms of performance.

Jorge Ramón • Jul 11 '19

Remember Worker as OS thread actually so I don't think they will be emulated in a single CPU core case. Anyway that's an interesting question but unfortunately workers are pretty "new" so there isn't enough information about them.

KP • Aug 2 '19

@jorge_rockr amazing article, i learned a lot about nodejs.
Question: I am building a mobile-responsive website, and my stack has Nuxt.js (vue.js framework) for the front end, talking to back-end APIs in Laravel (php framework). Nuxt.js is built on top of node (I think?) and I am using it for server-side-rendering. What are your thoughts on this architecture, versus using something purely in node.js?

Jorge Ramón • Aug 3 '19

Hi! Thanks you so much for reading my article.

Yeah, Nuxt.js and Next.js (React) are built on top of Node.js and it's cool since you can use your Frontend knowledge adding some Backend code.

In fact, using pure Node.js could have a better performance but it could be more complex and hard to maintain.

KP • Aug 3 '19

@jorge_rockr it was a phenomenal article, thank you for writing it.

Thanks for the recommendation. Sounds like I should stick with back-end APIs in Laravel, and use Nuxt for my front end. Hopefully I should see a lot of the user-benefits one can get from using Node with server-side-rendering for SEO.

Al Karlssen • Jul 15 '19

Node.js is also a variety of ready-to-use packages written for the Node.js, thanks to which we can easily connect to almost any service or database. The most common Node itechcraft.com/node-js/ integration dialect, however, is JSON, which speaks well with the NoSQL databases.

Technology Crowds • Aug 20 '20 • Edited

Excellent article!! Great Job! Really helpful for those who are new to NODE.JS .I cleared my all doubts regarding Node.js. Get more information about Node.js here.

Mary Krivokhat • Jan 6 '20

Jorge Ramón, thank you for this awesome article!)

The company I am working at, in January-February 2020 starts the open-source project for Node.js developers (microservices)!
Warm welcome🥳
Spectrum: spectrum.chat/yap?tab=posts (community chat)
GitBook: manual.youngapp.co/community-edition/ (docs)
Twitter: twitter.com/youngapp_pf (news)
GitHub: github.com/youngapp/yap (docs)
(click🌟star to support us and stay connected🙌)

Vesi Staneva • Jul 3 '20

Thank you for sharing this awesome post! Node.js rocks🤟

My team just completed an open-sourced Content Moderation Service built Node.js, TensorFlowJS, and ReactJS that we have been working over the past weeks. We have now released the first part of a series of three tutorials - How to create an NSFW Image Classification REST API and we would love to hear your feedback. Any comments & suggestions are more than welcome. Thanks in advance! 😊

Noorullah Ahmadzai • Jul 5 '19

Wow! Amazing Article!
Thanks for sharing ❤️

Maricaya • Sep 11 '20

Thanks for the great post!

Can I translate this article into Chinese so that more people can see it ?

Jorge Ramón • Nov 6 '20

Sure!!

Oliver Zulett • Apr 13 '20

Increible explicacion antes de este post no tenia ni la mas remota idea de como funcionaba Node.js en realidad, excelente

Jorge Ramón • May 8 '20

De nada!

Waleed Barakat • Jul 5 '19

Yes, it's very powerful, but how to build dynamic sites that uses mysql db like PHP?

Jorge Ramón • Jul 5 '19

If you want to build a site in a PHP style you need a template engine.

There are many templates engines out there. It's better to use Express Framework and any of the following templates engines:

expressjs.com/en/guide/using-templ...

But if you really love PHP you can use it with Express Framework too:

npmjs.com/package/php-express

Waleed Barakat • Jul 5 '19

Thank you :)

Danielle Hutchings • Sep 21 '19

As someone who is new to coding and just beginning to learn Node.js, this article was super helpful to get an overview of how Node.js works and why it's beneficial. Thanks for sharing!

Jorge Ramón • Sep 21 '19

Welcome! I'm glad it was useful for you

Comment marked as low quality/non-constructive by the community. View Code of Conduct

Devjeet Roy • Jan 4 '20

You might also like to visit : learnnodeonline.blogspot.com/
More blogs are about to come.

Omar Gaston Chalas • Jul 8 '19

Amazing! I'm surprised about how much you know about the internal process of Node.js, Can you suggest me some resources (aside of documentation) to learn advanced concepts?

Jorge Ramón • Jul 11 '19

Sorry for late response.

Take a look at this resources:

And check out this video to understand how Event Loop works (in browser but it's almost the same in Node.js).

Omar Gaston Chalas • Jul 11 '19

Thanks Jorge, i'm checking them out right now!

Buddhima Wickramasinghe • Jul 6 '19

Thanks for the great article.

Luis A. Ochoa R. • Jul 10 '19

Niceeeee post!

Bret Williams • Jul 11 '19

Nice overview Jorge. Question for you - with the advent of asynch enabled REST endpoints in .NET, specifically Web API, does this mitigate the C10M problem you referred to somewhat?

Jorge Ramón • Jul 11 '19 • Edited

According to Microsoft's official documentation:

For example, in Windows an OS thread makes a call to the network device driver and asks it to perform the networking operation via an Interrupt Request Packet (IRP) which represents the operation. The device driver receives the IRP, makes the call to the network, marks the IRP as "pending", and returns back to the OS. Because the OS thread now knows that the IRP is "pending", it doesn't have any more work to do for this job and "returns" back so that it can be used to perform other work.
When the request is fulfilled and data comes back through the device driver, it notifies the CPU of new data received via an interrupt. How this interrupt gets handled will vary depending on the OS, but eventually the data will be passed through the OS until it reaches a system interop call (for example, in Linux an interrupt handler will schedule the bottom half of the IRQ to pass the data up through the OS asynchronously). Note that this also happens asynchronously! The result is queued up until the next available thread is able to execute the async method and "unwrap" the result of the completed task.
Throughout this entire process, a key takeaway is that no thread is dedicated to running the task. Although work is executed in some context (that is, the OS does have to pass data to a device driver and respond to an interrupt), there is no thread dedicated to waiting for data from the request to come back. This allows the system to handle a much larger volume of work rather than waiting for some I/O call to finish.

Please note there is no thread dedicated to waiting for data from the request to come back, so that means they are not using Reactor Pattern (i.e. an Event Loop), they are really using purely OS resources (threads and interrupts) and that is awesome!!

I don't know if that's enough to solve C10M problem, maybe with big server resources such as 128 RAM, etc.

Maricaya • Sep 11 '20

Thanks for the great post!

Vanessa Osuka • Jul 9 '19

thanks for explaining worker threads more clearly!