Cluster

Cluster is an extensible multi-core server manager for node.js.

Installation

$ npm install cluster

Features

• zero-downtime restart
• hard shutdown support
• graceful shutdown support
• resuscitates workers
• maintains worker count, even if worker was _SIGKILL_ed.
• workers commit suicide when master dies
• spawns one worker per cpu (by default)
• extensible via plugins
• bundled plugins
  • cli: provides a command-line interface for your cluster
  • debug: verbose debugging information
  • logger: master / worker logs
  • pidfiles: writes master / worker pidfiles
  • reload: reloads workers when files change
  • repl: perform real-time administration
  • stats: adds real-time statistics to the repl plugin
• supports node 0.2.x
• supports node 0.4.x
• supports TCP servers

Example

app.js:

var http = require('http');

module.exports = http.createServer(function(req, res){
  console.log('%s %s', req.method, req.url);
  var body = 'Hello World';
  res.writeHead(200, { 'Content-Length': body.length });
  res.end(body);
});

server.js:

var cluster = require('cluster')
  , app = require('./app');

cluster(app)
  .use(cluster.logger('logs'))
  .use(cluster.stats())
  .use(cluster.pidfiles('pids'))
  .use(cluster.cli())
  .use(cluster.repl(8888))
  .listen(3000);

Note that cluster does not create these directories for you, so you may want to:

$ mkdir {logs,pids}

recommended usage: passing the path to prevent unnecessary database connections in the master process, as ./app is only require()ed within the workers.

var cluster = require('cluster');

cluster('./app')
  .use(cluster.logger('logs'))
  .use(cluster.stats())
  .use(cluster.pidfiles('pids'))
  .use(cluster.cli())
  .use(cluster.repl(8888))
  .listen(3000);

Plugins

Below are the known 3rd-party plugins for cluster:

• cluster-log remote logger powered by redis
• cluster-mail email exception notifications
• cluster-exception extensive exception notifications
• cluster-responsetimes response time statistics for cluster's REPL
• cluster-vhost add virtual host support to cluster

Screencasts

• Cluster Introduction

Running Tests

Install development dependencies:

$ npm install

Then:

$ make test

Actively tested with node:

• 0.4.9

Authors

• TJ Holowaychuk

License

(The MIT License)

Copyright (c) 2011 LearnBoost <dev@learnboost.com>

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.