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cluster: clean up lib/cluster.js 

Clean up and DRY the cluster source code. Fix a few bugs while we're
here:

* Short-lived handles in long-lived worker processes were never
  reclaimed, resulting in resource leaks.

* Handles in the master process are now closed when the last worker
  that holds a reference to them quits. Previously, they were only
  closed at cluster shutdown.

* The cluster object no longer exposes functions/properties that are
  only valid in the 'other' process, e.g. cluster.fork() is no longer
  exported in worker processes.

So much goodness and still manages to reduce the line count from 590
to 320.
v0.11.2-release
Ben Noordhuis 12 years ago
parent
c77312405e
commit
41b75ca926
1 changed files with 237 additions and 505 deletions
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  1. 728
      lib/cluster.js

728
lib/cluster.js
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@ -19,572 +19,304 @@
// OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE // OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
// USE OR OTHER DEALINGS IN THE SOFTWARE. // USE OR OTHER DEALINGS IN THE SOFTWARE.
var EventEmitter = require('events').EventEmitter;
var assert = require('assert'); var assert = require('assert');
var dgram = require('dgram');
var fork = require('child_process').fork; var fork = require('child_process').fork;
var net = require('net'); var net = require('net');
var EventEmitter = require('events').EventEmitter;
var util = require('util'); var util = require('util');
function isObject(o) { var cluster = new EventEmitter;
return (typeof o === 'object' && o !== null); module.exports = cluster;
} cluster.Worker = Worker;
cluster.isWorker = ('NODE_UNIQUE_ID' in process.env);
cluster.isMaster = (cluster.isWorker === false);
var debug;
if (process.env.NODE_DEBUG && /cluster/.test(process.env.NODE_DEBUG)) {
debug = function(x) {
var prefix = process.pid + ',' +
(process.env.NODE_UNIQUE_ID ? 'Worker' : 'Master');
console.error(prefix, x);
};
} else {
debug = function() { };
}
// cluster object: function Worker() {
function Cluster() { if (!(this instanceof Worker)) return new Worker;
EventEmitter.call(this); EventEmitter.call(this);
this.suicide = undefined;
this.state = 'none';
this.id = 0;
} }
util.inherits(Worker, EventEmitter);
util.inherits(Cluster, EventEmitter); Worker.prototype.kill = function() {
this.destroy.apply(this, arguments);
var cluster = module.exports = new Cluster(); };
// Used in the master:
var masterStarted = false;
var ids = 0;
var serverHandlers = {};
// Used in the worker: Worker.prototype.send = function() {
var serverListeners = {}; this.process.send.apply(this.process, arguments);
var queryIds = 0; };
var queryCallbacks = {};
// Define isWorker and isMaster // Master/worker specific methods are defined in the *Init() functions.
cluster.isWorker = 'NODE_UNIQUE_ID' in process.env;
cluster.isMaster = ! cluster.isWorker;
// The worker object is only used in a worker
cluster.worker = cluster.isWorker ? {} : null;
// The workers array is only used in the master
cluster.workers = cluster.isMaster ? {} : null;
// Settings object if (cluster.isMaster)
var settings = cluster.settings = {}; masterInit();
else
workerInit();
// Simple function to call a function on each worker
function eachWorker(cb) {
// Go through all workers
for (var id in cluster.workers) {
if (cluster.workers.hasOwnProperty(id)) {
cb(cluster.workers[id]);
}
}
}
// Extremely simple progress tracker function masterInit() {
function ProgressTracker(missing, callback) { cluster.workers = {};
this.missing = missing;
this.callback = callback;
}
ProgressTracker.prototype.done = function() {
this.missing -= 1;
this.check();
};
ProgressTracker.prototype.check = function() {
if (this.missing === 0) this.callback();
};
cluster.setupMaster = function(options) { var intercom = new EventEmitter;
// This can only be called from the master. var settings = {
assert(cluster.isMaster); args: process.argv.slice(2),
exec: process.argv[1],
// Don't allow this function to run more than once execArgv: process.execArgv,
if (masterStarted) return; silent: false
masterStarted = true; };
cluster.settings = settings;
// Get filename and arguments
options = options || {}; // Indexed by address:port:etc key. Its entries are dicts with handle and
// workers keys. That second one is a list of workers that hold a reference
// By default, V8 writes the profile data of all processes to a single // to the handle. When a worker dies, we scan the dicts and close the handle
// v8.log. // when its reference count drops to zero. Yes, that means we're doing an
// // O(n*m) scan but n and m are small and worker deaths are rare events anyway.
// Running that log file through a tick processor produces bogus numbers var handles = {};
// because many events won't match up with the recorded memory mappings
// and you end up with graphs where 80+% of ticks is unaccounted for. var initialized = false;
// cluster.setupMaster = function(options) {
// Fixing the tick processor to deal with multi-process output is not very if (initialized === true) return;
// useful because the processes may be running wildly disparate workloads. initialized = true;
// settings = util._extend(settings, options || {});
// That's why we fix up the command line arguments to include // Tell V8 to write profile data for each process to a separate file.
// a "--logfile=v8-%p.log" argument (where %p is expanded to the PID) // Without --logfile=v8-%p.log, everything ends up in a single, unusable
// unless it already contains a --logfile argument. // file. (Unusable because what V8 logs are memory addresses and each
var execArgv = options.execArgv || process.execArgv; // process has its own memory mappings.)
if (execArgv.some(function(s) { return /^--prof/.test(s); }) && if (settings.execArgv.some(function(s) { return /^--prof/.test(s); }) &&
!execArgv.some(function(s) { return /^--logfile=/.test(s); })) !settings.execArgv.some(function(s) { return /^--logfile=/.test(s); }))
{ {
execArgv = execArgv.slice(); settings.execArgv = settings.execArgv.concat(['--logfile=v8-%p.log']);
execArgv.push('--logfile=v8-%p.log');
} }
cluster.settings = settings;
// Set settings object
settings = cluster.settings = {
exec: options.exec || process.argv[1],
execArgv: execArgv,
args: options.args || process.argv.slice(2),
silent: options.silent || false
};
// emit setup event
cluster.emit('setup'); cluster.emit('setup');
}; };
// Check if a message is internal only
var INTERNAL_PREFIX = 'NODE_CLUSTER_';
function isInternalMessage(message) {
return isObject(message) &&
typeof message.cmd === 'string' &&
message.cmd.length > INTERNAL_PREFIX.length &&
message.cmd.slice(0, INTERNAL_PREFIX.length) === INTERNAL_PREFIX;
}
// Modify message object to be internal
function internalMessage(inMessage) {
var outMessage = util._extend({}, inMessage);
// Add internal prefix to cmd
outMessage.cmd = INTERNAL_PREFIX + (outMessage.cmd || '');
return outMessage;
}
// Handle callback messages
function handleResponse(outMessage, outHandle, inMessage, inHandle, worker) {
// The message there will be sent
var message = internalMessage(outMessage);
// callback id - will be undefined if not set var ids = 0;
message._queryEcho = inMessage._requestEcho; cluster.fork = function(env) {
cluster.setupMaster();
var worker = new Worker;
worker.id = ++ids;
var workerEnv = util._extend({}, process.env);
workerEnv = util._extend(workerEnv, env);
workerEnv.NODE_UNIQUE_ID = '' + worker.id;
worker.process = fork(settings.exec, settings.args, {
env: workerEnv,
silent: settings.silent,
execArgv: settings.execArgv
});
worker.process.once('exit', function(exitCode, signalCode) {
worker.suicide = !!worker.suicide;
worker.state = 'dead';
worker.emit('exit', exitCode, signalCode);
cluster.emit('exit', worker, exitCode, signalCode);
delete cluster.workers[worker.id];
});
worker.process.once('disconnect', function() {
worker.suicide = !!worker.suicide;
worker.state = 'disconnected';
worker.emit('disconnect');
cluster.emit('disconnect', worker);
delete cluster.workers[worker.id];
});
worker.process.on('error', worker.emit.bind(worker, 'error'));
worker.process.on('message', worker.emit.bind(worker, 'message'));
worker.process.on('internalMessage', internal(worker, onmessage));
process.nextTick(function() {
cluster.emit('fork', worker);
});
cluster.workers[worker.id] = worker;
return worker;
};
// Call callback if a query echo is received cluster.disconnect = function(cb) {
if (inMessage._queryEcho) { for (var key in cluster.workers) {
queryCallbacks[inMessage._queryEcho](inMessage.content, inHandle); var worker = cluster.workers[key];
delete queryCallbacks[inMessage._queryEcho]; worker.disconnect();
} }
if (cb) intercom.once('disconnect', cb);
};
// Send if outWrap contains something useful cluster.on('disconnect', function(worker) {
if (!(outMessage === undefined && message._queryEcho === undefined)) { delete cluster.workers[worker.id];
sendInternalMessage(worker, message, outHandle); // O(n*m) scan but for small values of n and m.
for (var key in handles) {
var e = handles[key];
var i = e.workers.indexOf(worker);
if (i === -1) continue;
e.workers.splice(i, 1);
if (e.workers.length !== 0) continue;
e.handle.close();
delete handles[key];
} }
} if (Object.keys(handles).length === 0) {
intercom.emit('disconnect');
// Handle messages from both master and workers
var messageHandler = {};
function handleMessage(worker, inMessage, inHandle) {
// Remove internal prefix
var message = util._extend({}, inMessage);
message.cmd = inMessage.cmd.substr(INTERNAL_PREFIX.length);
var respondUsed = false;
function respond(outMessage, outHandler) {
respondUsed = true;
handleResponse(outMessage, outHandler, inMessage, inHandle, worker);
} }
});
// Run handler if it exists Worker.prototype.disconnect = function() {
if (messageHandler[message.cmd]) { this.suicide = true;
messageHandler[message.cmd](message, worker, respond); send(this, { act: 'disconnect' });
} };
// Send respond if it hasn't been called yet Worker.prototype.destroy = function(signo) {
if (respondUsed === false) { signo = signo || 'SIGTERM';
respond(); var proc = this.process;
if (proc.connected) {
proc.once('disconnect', proc.kill.bind(proc, signo));
proc.disconnect();
return;
} }
} proc.kill(signo);
};
// Messages to the master will be handled using these methods function onmessage(message, handle) {
if (cluster.isMaster) { var worker = this;
if (message.act === 'online')
online(worker);
else if (message.act === 'queryServer')
queryServer(worker, message);
else if (message.act === 'listening')
listening(worker, message);
else if (message.act === 'suicide')
worker.suicide = true;
}
// Handle online messages from workers function online(worker) {
messageHandler.online = function(message, worker) {
worker.state = 'online'; worker.state = 'online';
debug('Worker ' + worker.process.pid + ' online');
worker.emit('online'); worker.emit('online');
cluster.emit('online', worker); cluster.emit('online', worker);
}; }
// Handle queryServer messages from workers
messageHandler.queryServer = function(message, worker, send) {
// This sequence of information is unique to the connection function queryServer(worker, message) {
// but not to the worker
var args = [message.address, var args = [message.address,
message.port, message.port,
message.addressType, message.addressType,
message.fd]; message.fd];
var key = args.join(':'); var key = args.join(':');
var handler; var e = handles[key];
if (typeof e === 'undefined') {
if (serverHandlers.hasOwnProperty(key)) { e = { workers: [] };
handler = serverHandlers[key]; if (message.addressType === 'udp4' || message.addressType === 'udp6')
} else if (message.addressType === 'udp4' || e.handle = dgram._createSocketHandle.apply(null, args);
message.addressType === 'udp6') { else
var dgram = require('dgram'); e.handle = net._createServerHandle.apply(null, args);
handler = dgram._createSocketHandle.apply(net, args); handles[key] = e;
serverHandlers[key] = handler; }
} else { e.workers.push(worker);
handler = net._createServerHandle.apply(net, args); send(worker, { ack: message.seq }, e.handle);
serverHandlers[key] = handler;
} }
// echo callback with the fd handler associated with it function listening(worker, message) {
send({}, handler); var info = {
};
// Handle listening messages from workers
messageHandler.listening = function(message, worker) {
worker.state = 'listening';
// Emit listening, now that we know the worker is listening
worker.emit('listening', {
address: message.address,
port: message.port,
addressType: message.addressType, addressType: message.addressType,
fd: message.fd
});
cluster.emit('listening', worker, {
address: message.address, address: message.address,
port: message.port, port: message.port,
addressType: message.addressType,
fd: message.fd fd: message.fd
});
};
// Handle suicide messages from workers
messageHandler.suicide = function(message, worker) {
worker.suicide = true;
};
}
// Messages to a worker will be handled using these methods
else if (cluster.isWorker) {
// Handle worker.disconnect from master
messageHandler.disconnect = function(message, worker) {
worker.disconnect();
}; };
} worker.state = 'listening';
worker.emit('listening', info);
function toDecInt(value) { cluster.emit('listening', worker, info);
value = parseInt(value, 10);
return isNaN(value) ? null : value;
}
// Create a worker object, that works both for master and worker
function Worker(customEnv) {
if (!(this instanceof Worker)) return new Worker();
EventEmitter.call(this);
var self = this;
var env = process.env;
// Assign a unique id, default null
this.id = cluster.isMaster ? ++ids : toDecInt(env.NODE_UNIQUE_ID);
// XXX: Legacy. Remove in 0.9
this.workerID = this.uniqueID = this.id;
// Assign state
this.state = 'none';
// Create or get process
if (cluster.isMaster) {
// Create env object
// first: copy and add id property
var envCopy = util._extend({}, env);
envCopy['NODE_UNIQUE_ID'] = this.id;
// second: extend envCopy with the env argument
if (isObject(customEnv)) {
envCopy = util._extend(envCopy, customEnv);
}
// fork worker
this.process = fork(settings.exec, settings.args, {
'env': envCopy,
'silent': settings.silent,
'execArgv': settings.execArgv
});
} else {
this.process = process;
}
if (cluster.isMaster) {
// Save worker in the cluster.workers array
cluster.workers[this.id] = this;
// Emit a fork event, on next tick
// There is no worker.fork event since this has no real purpose
process.nextTick(function() {
cluster.emit('fork', self);
});
}
// handle internalMessage, exit and disconnect event
this.process.on('internalMessage', handleMessage.bind(null, this));
this.process.once('exit', function(exitCode, signalCode) {
prepareExit(self, 'dead');
self.emit('exit', exitCode, signalCode);
cluster.emit('exit', self, exitCode, signalCode);
});
this.process.once('disconnect', function() {
prepareExit(self, 'disconnected');
self.emit('disconnect');
cluster.emit('disconnect', self);
});
// relay message and error
this.process.on('message', this.emit.bind(this, 'message'));
this.process.on('error', this.emit.bind(this, 'error'));
}
util.inherits(Worker, EventEmitter);
cluster.Worker = Worker;
function prepareExit(worker, state) {
// set state to disconnect
worker.state = state;
// Make suicide a boolean
worker.suicide = !!worker.suicide;
// Remove from workers in the master
if (cluster.isMaster) {
delete cluster.workers[worker.id];
}
}
// Send internal message
function sendInternalMessage(worker, message/*, handler, callback*/) {
// Exist callback
var callback = arguments[arguments.length - 1];
if (typeof callback !== 'function') {
callback = undefined;
}
// exist handler
var handler = arguments[2] !== callback ? arguments[2] : undefined;
if (!isInternalMessage(message)) {
message = internalMessage(message);
} }
// Store callback for later function send(worker, message, handle, cb) {
if (callback) { sendHelper(worker.process, message, handle, cb);
message._requestEcho = worker.id + ':' + (++queryIds);
queryCallbacks[message._requestEcho] = callback;
} }
worker.send(message, handler);
} }
// Send message to worker or master
Worker.prototype.send = function() {
// You could also just use process.send in a worker
this.process.send.apply(this.process, arguments);
};
// Kill the worker without restarting function workerInit() {
Worker.prototype.kill = Worker.prototype.destroy = function(signal) { var handles = [];
if (!signal)
signal = 'SIGTERM';
var self = this;
this.suicide = true;
if (cluster.isMaster) { // Called from src/node.js
// Disconnect IPC channel cluster._setupWorker = function() {
// this way the worker won't need to propagate suicide state to master var worker = new Worker;
if (self.process.connected) { cluster.worker = worker;
self.process.once('disconnect', function() { worker.id = +process.env.NODE_UNIQUE_ID | 0;
self.process.kill(signal); worker.state = 'online';
}); worker.process = process;
self.process.disconnect(); process.once('disconnect', process.exit.bind(null, 0));
} else { process.on('internalMessage', internal(worker, onmessage));
self.process.kill(signal); send({ act: 'online' });
function onmessage(message, handle) {
if (message.act === 'disconnect') worker.disconnect();
} }
};
} else { // obj is a net#Server or a dgram#Socket object.
// Channel is open cluster._getServer = function(obj, address, port, addressType, fd, cb) {
if (this.process.connected) { var message = {
addressType: addressType,
// Inform master to suicide and then kill address: address,
sendInternalMessage(this, {cmd: 'suicide'}, function() { port: port,
process.exit(0); act: 'queryServer',
fd: fd
};
send(message, function(_, handle) {
// Monkey-patch the close() method so we can keep track of when it's
// closed. Avoids resource leaks when the handle is short-lived.
var close = handle.close;
handle.close = function() {
var index = handles.indexOf(handle);
if (index !== -1) handles.splice(index, 1);
return close.apply(this, arguments);
};
handles.push(handle);
cb(handle);
}); });
obj.once('listening', function() {
// When channel is closed, terminate the process cluster.worker.state = 'listening';
this.process.once('disconnect', function() { message.act = 'listening';
process.exit(0); message.port = obj.address().port || port;
send(message);
}); });
} else {
process.exit(0);
}
}
};
// The .disconnect function will close all servers
// and then disconnect the IPC channel.
if (cluster.isMaster) {
// Used in master
Worker.prototype.disconnect = function() {
this.suicide = true;
sendInternalMessage(this, {cmd: 'disconnect'});
}; };
} else {
// Used in workers
Worker.prototype.disconnect = function() { Worker.prototype.disconnect = function() {
var self = this; for (var handle; handle = handles.shift(); handle.close());
process.disconnect();
this.suicide = true;
// keep track of open servers
var servers = Object.keys(serverListeners).length;
var progress = new ProgressTracker(servers, function() {
// There are no more servers open so we will close the IPC channel.
// Closing the IPC channel will emit a disconnect event
// in both master and worker on the process object.
// This event will be handled by prepareExit.
self.process.disconnect();
});
// depending on where this function was called from (master or worker)
// The suicide state has already been set,
// but it doesn't really matter if we set it again.
sendInternalMessage(this, {cmd: 'suicide'}, function() {
// in case there are no servers
progress.check();
// closing all servers gracefully
var server;
for (var key in serverListeners) {
server = serverListeners[key];
// in case the server is closed we won't close it again
if (server._handle === null) {
progress.done();
continue;
}
server.on('close', progress.done.bind(progress));
server.close();
}
});
}; };
}
// Fork a new worker Worker.prototype.destroy = function() {
cluster.fork = function(env) { if (!process.connected) process.exit(0);
// This can only be called from the master. var exit = process.exit.bind(null, 0);
assert(cluster.isMaster); send({ act: 'suicide' }, exit);
process.once('disconnect', exit);
// Make sure that the master has been initialized process.disconnect();
cluster.setupMaster(); };
return (new cluster.Worker(env));
};
// execute .disconnect on all workers and close handlers when done function send(message, cb) {
cluster.disconnect = function(callback) { sendHelper(process, message, null, cb);
// This can only be called from the master.
assert(cluster.isMaster);
// Close all TCP handlers when all workers are disconnected
var workers = Object.keys(cluster.workers).length;
var progress = new ProgressTracker(workers, function() {
for (var key in serverHandlers) {
serverHandlers[key].close();
delete serverHandlers[key];
} }
}
// call callback when done
if (callback) callback();
});
// begin disconnecting all workers
eachWorker(function(worker) {
worker.once('disconnect', progress.done.bind(progress));
worker.disconnect();
});
// in case there weren't any workers
progress.check();
};
// Internal function. Called from src/node.js when worker process starts. var seq = 0;
cluster._setupWorker = function() { var callbacks = {};
function sendHelper(proc, message, handle, cb) {
// Mark message as internal. See INTERNAL_PREFIX in lib/child_process.js
message = util._extend({ cmd: 'NODE_CLUSTER' }, message);
if (cb) callbacks[seq] = cb;
message.seq = seq;
seq += 1;
proc.send(message, handle);
}
// Get worker class
var worker = cluster.worker = new Worker();
// we will terminate the worker // Returns an internalMessage listener that hands off normal messages
// when the worker is disconnected from the parent accidentally // to the callback but intercepts and redirects ACK messages.
process.once('disconnect', function() { function internal(worker, cb) {
if (worker.suicide !== true) { return function(message, handle) {
process.exit(0); if (message.cmd !== 'NODE_CLUSTER') return;
var fn = cb;
if (typeof message.ack !== 'undefined') {
fn = callbacks[message.ack];
delete callbacks[message.ack];
} }
}); fn.apply(worker, arguments);
// Tell master that the worker is online
worker.state = 'online';
sendInternalMessage(worker, { cmd: 'online' });
};
// Internal function. Called by net.js and dgram.js when attempting to bind a
// TCP server or UDP socket.
cluster._getServer = function(tcpSelf, address, port, addressType, fd, cb) {
// This can only be called from a worker.
assert(cluster.isWorker);
// Store tcp instance for later use
var key = [address, port, addressType, fd].join(':');
serverListeners[key] = tcpSelf;
// Send a listening message to the master
tcpSelf.once('listening', function() {
cluster.worker.state = 'listening';
sendInternalMessage(cluster.worker, {
cmd: 'listening',
address: address,
port: tcpSelf.address().port || port,
addressType: addressType,
fd: fd
});
});
// Request the fd handler from the master process
var message = {
cmd: 'queryServer',
address: address,
port: port,
addressType: addressType,
fd: fd
}; };
}
// The callback will be stored until the master has responded
sendInternalMessage(cluster.worker, message, function(msg, handle) {
cb(handle);
});
};

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