July 2020
Intermediate to advanced
608 pages
15h 43m
English
Content preview from JavaScript
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16Shared Memory
In this chapter, you'll learn about JavaScript's shared memory feature (in ES2017+), allowing memory to be shared between threads, and the Atomics object you can use to perform low-level shared memory operations and to suspend and resume threads based on events in shared memory.
INTRODUCTION
For most of the decade or so that JavaScript on browsers hasn't been single-threaded (thanks to web workers), there was no way to share memory across threads in the browser. Initially, threads could post messages to each other with data in them, but the data was copied. When it's a lot of data, or it has to be sent back and forth a lot, that's a problem. A few years later when typed arrays (Chapter 11) were defined, originally outside JavaScript and then added to ES2015, in many cases it became possible to transfer data from one thread to another without copying it, but the sending thread had to give up access to the data being sent.
ES2017 changed that with SharedArrayBuffer. With a SharedArrayBuffer, JavaScript code running in one thread can share memory with JavaScript code running on another thread.
Before getting into how shared memory works in JavaScript, let's explore the question of whether you really ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.