why-is-node-running

What is why-is-node-running?

The why-is-node-running package is a Node.js module that helps developers diagnose why a Node.js process hasn't exited on its own. It provides insights into what operations are keeping the event loop busy, such as open handles, active timers, and other system tasks that may prevent the process from exiting.

What are why-is-node-running's main functionalities?

Logging active handles

This feature allows you to log all active handles that are currently preventing Node.js from exiting. It's useful for identifying potential sources of memory leaks or unintended behavior.

const log = require('why-is-node-running');

// somewhere in your long-running program
log(); // logs out active handles that are keeping node running

Logging with a delay

This feature is similar to the previous one, but it allows you to set a delay before logging the active handles. This can be useful when you want to give your application some time to settle before checking what is still running.

const log = require('why-is-node-running');

setTimeout(function () {
  log(); // logs out active handles after a delay
}, 10000);

Other packages similar to why-is-node-running

wtfnode

WTFNode is similar to why-is-node-running in that it helps to diagnose what is keeping a Node.js process running. It provides detailed output about timers, sockets, and other resources. It differs in its output format and the level of detail provided.

node-report

Node-report is an npm package that provides a diagnostic report on demand or when certain events occur. It's more comprehensive than why-is-node-running, offering information about the system, resource usage, and JavaScript stack trace, but it's not as focused on the reasons why a Node.js process is still running.

README

why-is-node-running

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

npm install why-is-node-running

Usage

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

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

createServer()
createServer()

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

Running the above will print

There are 4 known handle(s) keeping the process running and 0 unknown
Known handles:

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

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

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

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

License

MIT