Spawn network processes only when they are needed.
Fetching latest commit…
Cannot retrieve the latest commit at this time.
Failed to load latest commit information.


Save precious system resources by creating lazy network services that are only spawned when required.


Slacker listens for arbitrary TCP connections on behalf of your resource hungry processes, allowing them to remain dormant until required.

When a request for that service comes in, slacker buffers the request, boots the service if it is not already running, and forwards the connection to the service; this is only feasible because node processes boot reasonably quickly (<10ms).

After a specified timeout, if all the connections are closed and there are no new connections, slacker will shutdown/terminate the worker process, until the next request for it arrives.

Slacker should support any protocol built on top of TCP, such as HTTP, MQTT and WebSockets.


var slacker = require('slacker')

slacker(__dirname + '/some-http-service.js') // service to forward requests to
.timeout(10000) // service will be shut down after 10s of no active connections (default)
.listen(9000, function(err, port) { // listen on port 9000
  if (err) return console.error(err)
  console.log('slacker listening on %d', port)


If you have a process or number of processes that need to respond to network events but consume an unsustainable amount of system resources while they are running, it is efficient to simply shut these services down while they are not required!

Node doesn't currently have a non-hacky, reliable mechnism for unloading modules from memory, and this is ok, because there's a good workaround: The easiest way to clean up memory and prevent unnecessary idle work is to just isolate that work to a process and kill it when it is no longer required. This is the job of slacker.

Node 0.8.x support

Normally, slacker can deduce what port your worker is listening on but if you're using node < 0.9.2 this feature, mean you must manually have your worker tell the slacker process what port it's listening on:

Node 0.8.x Example

//In the app you want spawned by slacker
var app = http.createServer()
app.listen(function() {
  process.send && process.send(app.address()) // Node < 0.9.2 support

If you're using node 0.9.2 and above, you do not need to do this.