background preloader

Understanding the node.js event loop

Understanding the node.js event loop
So the largest waste with current programming technologies comes from waiting for I/O to complete. There are several ways in which one can deal with the performance impact (from Sam Rushing): The second basis thesis is that thread-per-connection is memory-expensive: [e.g. that graph everyone showns about Apache sucking up memory compared to Nginx] Apache is multithreaded: it spawns a thread per request (or process, it depends on the conf). You can see how that overhead eats up memory as the number of concurrent connections increases and more threads are needed to serve multiple simulataneous clients. There is no way of making code run in parallel within a single request. If you do that in one request, other requests can be processed just fine while the database is running it's sleep. Having asynchronous I/O is good, because I/O is more expensive than most code and we should be doing something better than just waiting for I/O. First-class functions. E.g. I really enjoyed your article. Ed, ed Related:  Introduction to Node.js and why it's faster than JavaNodeJs

Understanding node.js Node.js обычно вызывал у людей, которым я о нём рассказывал, две различные реакции. В основном они воспринимали его «как есть», однако многие были сбиты с толку. Если вы относитесь ко второй группе, я попробую объяснить, что же такое Node.js: Это инструмент командной строки. Вы скачиваете архив, компилируете и устанавливаете его.Это позволит вам выполнять программы на JavaScript, набрав 'node my_app.js' в терминале.JavaScript выполняется движком V8 (тем самым, благодаря которому так быстро работает Google Chrome).Node.js предоставляет API для доступа к сети и файловой системе из JavaScript.«Но я могу сделать то, что мне необходимо, с помощью Python, Ruby, Java, PHP,… !». Да, это я уже слышал. «Ближе к делу!» Хорошо. «Что?» Всё верно, всё выполняется параллельно, за исключением вашего кода. Каждый день начинается с того, что один слуга будит короля и спрашивает, нужно ли ему что-нибудь. Как только слуга завершает какую-то задачу, он приходит к царю и докладывает. Конечно. Вы это поняли!

StrongLoop | What Makes Node.js Faster Than Java? Every few weeks someone posts a Java vs Node benchmark, like PayPal’s or Joey Whelan’s. As one of maintainers of Node core and contributors to many npm modules, StrongLoop is happy to see Node winning lately. Everyone knows benchmarks are a specific measurement and don’t account for all cases. Sometimes Java is faster. High concurrency matters But there’s one thing we can all agree on: At high levels of concurrency (thousands of connections) your server needs to go to asynchronous non-blocking. While Java or Node or something else may win a benchmark, no server has the non-blocking ecosystem of Node.js today. Big companies, committed vendors and engaged community We’re going to help keep maturing Node and the ecosystem of tools and libraries as well. Use StrongOps to Monitor Node Apps Ready to start monitoring event loops, manage Node clusters and chase down memory leaks? Get trained in Node.js and API development Looking for Node.js and API development training? What’s next?

What is Node.js? | Charles Wang Node.js is an event-driven, non-blocking I/O model. It is a server side JavaScript environment that is based on the V8 JavaScript Engine developed by Google.The V8 JavaScript Engine allows Chrome to run Javascript code much faster. It is able to do this by compiling the JavaScript directly into native machine code. Other browsers interpret JavaScript, or execute it as byte code. What are some benefits for using JavaScript and node.js for server side programming? Both the front and back end of the a web application can be developed in the same languageminimize developer learning curvesminimize developer context switches What are modules in Node.js? Node uses modules which are libraries that extend its functionality. When should you use Node.js? You want to use Node.js in applications that require: Heavy I/OEvent-driven behaviorHigh Scalability (i.e. many clients)When your application requires a persistent connection to the server for connection to the server for continuous data transfer.

Scaling Node.js Applications | Colin J. Ihrig's Blog Scaling Node.js applications can be a challenge. JavaScript’s single threaded nature prevents Node from taking advantage of modern multi-core machines. For example, the following code implements a bare bones HTTP server, which listens on the port number passed in from the command line. This code will execute in a single thread, whether it’s run on a single core machine or a 1,000 core machine. Taking Advantage of Multiple Cores With a little work, the previous code can be modified to utilize all of the available cores on a machine. Scaling Across Machines Nodejitsu has developed node-http-proxy, an open source proxy server for Node applications. npm install http-proxy The actual reverse proxy server is shown below. Of course, this example only uses one machine. Scaling Using nginx Using a Node reverse proxy is nice because it keeps your entire software stack in the same technology. As I mentioned, for the purposes of this article, we are only interested in a few pieces of the file.

Java EE threads v/s Node.js - which is better for concurrent data processing operations | Tok We have started using NodeJS a lot these days typically to handle data processing applications that involve a large number of concurrent requests, each of which involve one or more I/O operations. Why Nodejs? Why not Java? What does the Data Processing Application do? The Data Processing Application is built to handle a large number of data flow processes that involve significant amount of I/O operations. Each process involves making calls to one or more database engines using network I/O. The Data Processing Application needs to execute a large number of concurrent API requests, each involving multiple network I/O operations. Java EE v/s NodeJS The most important differences between NodeJS and Java are the concurrency and I/O models. Let us examine how these differences affect The Data Processing Application’s ability to handle a large number of concurrent requests that involve multiple I/O operations. Concurrency Model Synchronous v/s Asynchronous I/O Scaling out to multiple CPUs Conclusion

11. File system - Mixu's Node book This chapter covers the file system module. The file system functions consist of file I/O and directory I/O functions. All of the file system functions offer both synchronous (blocking) and asynchronous (non-blocking) versions. The difference between these two is that the synchronous functions (which have “Sync” in their name) return the value directly and prevent Node from executing any code while the I/O operation is being performed: var fs = require('fs');var data = fs.readFileSync('./index.html', 'utf8');// wait for the result, then use it console.log(data); Asynchronous functions return the value as a parameter to a callback given to them: var fs = require('fs'); fs.readFile('. The table below lists all the asynchronous functions in the FS API. You should use the asynchronous version in most cases, but in rare cases (e.g. reading configuration files when starting a server) the synchronous version is more appropriate. fs.readFile('. fs.readFile('. 11.1 Files: reading and writing fs.open('.

hardware - Multithreading: What is the point of more threads than cores? 10 Habits of a Happy Node Hacker (2016) At the tail end of 2015, JavaScript developers have a glut of tools at our disposal. The last time we looked into this, the modern JS landscape was just emerging. Today, it's easy to get lost in our huge ecosystem, so successful teams follow guidelines to make the most of their time and keep their projects healthy. Here are ten habits for happy Node.js hackers as we enter 2016. 1. Npm's init command will scaffold out a valid package.json for your project, inferring common properties from the working directory. $ mkdir my-awesome-app $ cd my-awesome-app $ npm init --yes I'm lazy, so I run it with the --yes flag and then open package.json to make changes. 2. By default, npm doesn't save installed dependencies to package.json (and you should always track your dependencies!). If you use the --save flag to auto-update package.json, npm installs the packages with a leading carat (^), putting your modules at risk of drifting to different versions. One solution is installing packages like this: 3.

Related: