In this article, we would be seeing middlewares in NodeJS and how we would use them in our application. What are middlewares in Node.Js? Middlewares are functions used in connecting a bunch of isolated systems to interact and perform certain tasks. For example, think of a switch as a component and bulb as another independent component where a wire acts as a middleware to connect these both and give us the required output (In this case, electricity to light the bulb).

Here’s how you can generate a Node flame graph with linux perf(1). Note that perf(1) needs to run as root, but the perf.map file node generates might be owned by a different user. If that’s the case, you’ll need to change its ownership to root as well — otherwise perf(1) will not be able to use it to translate JS stack frames. $ uname -a Linux demo 3.2.0-74-virtual #109-Ubuntu SMP Tue Dec 9 17:04:48 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux