diff --git a/doc/api/cluster.markdown b/doc/api/cluster.markdown index 11184a5799..f4dc84650e 100644 --- a/doc/api/cluster.markdown +++ b/doc/api/cluster.markdown @@ -7,25 +7,57 @@ processes to handle the load. The cluster module allows you to easily create a network of processes all which share server ports. - var cluster = require('cluster'); - var http = require('http'); + var cluster = require('cluster'); + var http = require('http'); - if (!cluster.isWorker()) { - // Start the master process, fork workers. - cluster.startMaster({ workers: 2 }); - } else { - // Worker processes have a http server. - http.Server(function(req, res) { - res.writeHead(200); - res.end("hello world\n"); - }).listen(8000); - } + if (cluster.isMaster) { + // Start the master process, fork workers. + cluster.startMaster({ workers: 2 }); + } else { + // Worker processes have a http server. + http.Server(function(req, res) { + res.writeHead(200); + res.end("hello world\n"); + }).listen(8000); + } -If we start it like this +Running node will now share port 8000 between the workers: - % node cluster server.js - Detected 2 cpus + % node server.js Worker 2438 online Worker 2437 online -Node will automatically share port 8000 between the multiple instances. +### exports.startMaster([options]) + + Spawns the initial worker processes, one per CPU by default. + + The following options are supported: + + - `filename`: script to execute in the worker process, defaults to + `process.argv[1]` + - `args`: worker program arguments, defaulting to `process.argv.slice(2)` + - `workers`: the number of workers, defaulting to `os.cpus().length` + +### exports.spawnWorker([options]) + + Spawn a new worker process. This is called within `cluster.startMaster()`, + however it is useful to implement worker resuscitation as described below + in the "Common patterns" section. + + The `options` available are identical to `cluster.startMaster()`. + +## Common patterns + +## Worker resuscitation + +The following is an example of how you may implement worker resuscitation, +spawning a new worker process when another exits. + + if (cluster.isMaster) { + cluster.startMaster(); + process.on('SIGCHLD', function(){ + console.log('worker killed'); + cluster.spawnWorker(); + }); + } + diff --git a/lib/cluster.js b/lib/cluster.js index 38229c9986..8c45605442 100644 --- a/lib/cluster.js +++ b/lib/cluster.js @@ -47,14 +47,8 @@ var workerId = 0; var queryIds = 0; var queryCallbacks = {}; - - -// Used to check if this process is a worker or not. -// Returns boolean. -exports.isWorker = function() { - return 'NODE_WORKER_ID' in process.env; -}; - +exports.isWorker = 'NODE_WORKER_ID' in process.env; +exports.isMaster = ! exports.isWorker; // Call this from the master process. It will start child workers. //