why-is-node-running

Node is running but you don't know why? why-is-node-running is here to help you.

Installation

Node 8 and above:

npm i why-is-node-running -g

Earlier Node versions (no longer supported):

npm i [email protected] -g

Usage

const log = require('why-is-node-running') // should be your first require
const net = require('net')

function createServer () {
  const server = net.createServer()
  setInterval(function () {}, 1000)
  server.listen(0)
}

createServer()
createServer()

setTimeout(function () {
  log() // logs out active handles that are keeping node running
}, 100)

Save the file as example.js, then execute:

node ./example.js

Here's the output:

There are 5 handle(s) keeping the process running

# Timeout
/home/maf/dev/node_modules/why-is-node-running/example.js:6  - setInterval(function () {}, 1000)
/home/maf/dev/node_modules/why-is-node-running/example.js:10 - createServer()

# TCPSERVERWRAP
/home/maf/dev/node_modules/why-is-node-running/example.js:7  - server.listen(0)
/home/maf/dev/node_modules/why-is-node-running/example.js:10 - createServer()

# Timeout
/home/maf/dev/node_modules/why-is-node-running/example.js:6  - setInterval(function () {}, 1000)
/home/maf/dev/node_modules/why-is-node-running/example.js:11 - createServer()

# TCPSERVERWRAP
/home/maf/dev/node_modules/why-is-node-running/example.js:7  - server.listen(0)
/home/maf/dev/node_modules/why-is-node-running/example.js:11 - createServer()

# Timeout
/home/maf/dev/node_modules/why-is-node-running/example.js:13 - setTimeout(function () {

Important Note! unrefed timers do not prevent the Node process from exiting. If you are running with Node v11.0.0 and above, unrefed timers will not be listed in the above list. Unfortunately, this is not supported in node versions below v11.0.0.

CLI

You can also run why-is-node-running as a standalone if you don't want to include it inside your code. Sending SIGUSR1/SIGINFO signal to the process will produce the log. (Ctrl + T on macOS and BSD systems)

why-is-node-running /path/to/some/file.js

probing module /path/to/some/file.js
kill -SIGUSR1 31115 for logging

To trigger the log:

kill -SIGUSR1 31115

Require CLI Option

You can also use the node -r option to include why-is-node-running:

node -r why-is-node-running/include /path/to/some/file.js

The steps are otherwise the same as the above CLI section

License

MIT