Book Image

Mastering Node.js - Second Edition

By : Sandro Pasquali, Kevin Faaborg
Book Image

Mastering Node.js - Second Edition

By: Sandro Pasquali, Kevin Faaborg

Overview of this book

Node.js, a modern development environment that enables developers to write server- and client-side code with JavaScript, thus becoming a popular choice among developers. This book covers the features of Node that are especially helpful to developers creating highly concurrent real-time applications. It takes you on a tour of Node's innovative event non-blocking design, showing you how to build professional applications. This edition has been updated to cover the latest features of Node 9 and ES6. All code examples and demo applications have been completely rewritten using the latest techniques, introducing Promises, functional programming, async/await, and other cutting-edge patterns for writing JavaScript code. Learn how to use microservices to simplify the design and composition of distributed systems. From building serverless cloud functions to native C++ plugins, from chatbots to massively scalable SMS-driven applications, you'll be prepared for building the next generation of distributed software. By the end of this book, you'll be building better Node applications more quickly, with less code and more power, and know how to run them at scale in production environments.
Table of Contents (13 chapters)

Parsing a file using multiple processes

One of the tasks many developers will take on is the building of a logfile processor. A logfile can be very large and many megabytes long. Any single program working on a very large file can easily run into memory problems or simply run much too slowly. It makes sense to process a large file in pieces. We'll build a simple log processor that breaks up a big file into pieces and assigns one to each of several child workers, running them in parallel.

The entire code for this example can be found in the logproc folder of the code bundle. We will focus on the main routines:

  • Determining the number of lines in the logfile
  • Breaking those up into equal chunks
  • Creating one child for each chunk and passing it parse instructions
  • Assembling and displaying the results

To get the word count of our file, we use the wc command with child.exec, as...