Heroku: Up and Running

Chapter 3. Understanding Performance and Scale

When talking about performance in apps, two factors affect your users: speed and throughput. Speed is how fast your application can take a request and return a single response. Performance, when most people talk about it, refers to raw speed. Throughput is how many simultaneous requests can be handled at the same time. If speed is a drag racer screaming down the track, then throughput is thousands of participants crossing the line of a marathon.

Speed and throughput are closely related. If the throughput limit of your application isn’t high enough, then individual users will likely see slower response times, or no response at all. Likewise, speeding up individual requests with no other changes by definition means your app can process more requests per second. It’s important to account for both of these factors when considering performance. So, how can you make your app faster while handling more load at the same time? You’ll just have to keep reading to find out.

Horizontal Scaling and You

In the past, if you had an application that needed to handle more concurrent connections, you could increase the RAM, upgrade the hard drive, and buy a more expensive processor. This is known as vertical scaling; it is very easy to do but is limited. Eventually, you’ll max out your RAM slots or some other component. Instead of adding more capacity to a single computer, you can horizontally scale out by networking multiple computers together to form a ...