master-cluster
master-cluster is a utility to facilitate implementing node.js core cluster module
in any project. I created this module as I use the cluster module in pretty much all my projects and wanted to
remove the boilerplate code. It implements node.js core domain module
for correct exception handling. It also provides hot reloading of files on the worker in development mode
so that workers are restarted when code is changed.
Usage
In boot.js
:
var MC = require('master-cluster')
, worker = require.resolve('./server.js');
MC.start({exec: worker});
In server.js
:
var MC = require('master-cluster')
, app = require('./app.js')
, http = require('http');
// set the handler that will be used for all new requests
MC.setFnHandlers(app.index, shutdown);
// create the server and pass MC run handler
// each request will be wrap in a domain for exception handling
// so that workers are restarted automatically on crash
var server = http.createServer(MC.run);
server.listen(3000, function () {
console.log("Listening on %d", 3000);
});
function shutdown () {
// optional - cleanly close db connections and other resources
}
In app.js
:
function index (req, res) {
// do something with the request and response
}
exports.index = index;
Convenience http server method
The code above can be simplified if all you need is to start a http server.
In server.js
:
var MC = require('master-cluster')
, app = require('./app.js');
MC.createHttpServer(app.index, 3000, shutdown);
function shutdown () {
// cleanly close db connections and other resources
}
With express
var app = require('express')();
var MC = require('master-cluster');
var responseTime = require('response-time');
app.use(responseTime({ header: 'x-response-time' }));
app.get('/', function (req, res) {
res.end('Hello world');
});
MC.createHttpServer(app, 3000);
console.log('Server listening on %d', 3000);
Configuration
Following options can be passed to the master cluster configuration:
exec
: the code to run on the cluster mastersize
: the number of workers to start, default is require("os").cpus().length
reload
: boolean
, default is false
except when process.env.NODE_ENV == 'dev'
logger
: optional logger for errors (must implement error
method)
Reloader specific options:
cooldown
: number of milliseconds to wait between file changes, default is 100ms
extensions
: file extensions to watch for and reload on change, default to js
Worker options:
killTimeout
: timeout to kill the worker on uncaught exception (default 30s)logger
: optional logger for errors (must implement error
method)
Method handlers
start (options)
: start the master with cluster optionsrun ()
: worker http handler that runs the request wrapped in the domain error handlingsetFnHandlers (runFn, errorFn)
: set the run and error handlers for the domain modulesetOptions (options)
: set the options for the workers (logger and kill timeout)createHttpServer (handler, port, onShutdown)
: create the http server and setup the run and error handlers for the domain module
Miscellaneous
cluster
: expose the exported cluster module
Disclaimer
This module is still experimental and subject to change. Please open issues for bugs and suggestions in github.
Pull requests welcome.
Author
Jerome Touffe-Blin, @jtblin, http://www.linkedin.com/in/jtblin
License
master-cluster is copyright 2013 Jerome Touffe-Blin and contributors. It is licensed under the BSD license. See the include LICENSE file for details.