目前，我面临的任务是使用Amazon EC2扩展Node.js应用程序。据我所知，做法是每个子服务器都使用集群(cluster)来使用所有可用进程，并使用粘性连接(sticky connections)确保连接到服务器的每个用户在以前的会话中“记住”他们当前所在的工作进程(worker)。
在这样做之后，从我所知道的情况来看，下一步最好的方法是部署所需的所有服务器，并使用nginx在它们之间进行负载平衡，再次使用粘性连接(sticky connections)来知道每个用户数据所在的“子”服务器。
那么当用户连接到服务器时，会发生什么呢？
客户端连接 -> 查找/选择服务器 -> 查找/选择进程 -> Socket.IO握手/连接等。
如果不是这样，请让我更好地理解这个负载平衡任务。我也不明白在这种情况下redis的重要性。
以下是我正在使用的代码，用于将一个单独的Node.js进程上的所有CPU用于另一个进程：
var express = require('express');
cluster = require('cluster'),
net = require('net'),
sio = require('socket.io'),
sio_redis = require('socket.io-redis');
var port = 3502,
num_processes = require('os').cpus().length;
if (cluster.isMaster) {
// This stores our workers. We need to keep them to be able to reference
// them based on source IP address. It's also useful for auto-restart,
// for example.
var workers = [];
// Helper function for spawning worker at index 'i'.
var spawn = function(i) {
workers[i] = cluster.fork();
// Optional: Restart worker on exit
workers[i].on('exit', function(worker, code, signal) {
console.log('respawning worker', i);
spawn(i);
});
};
// Spawn workers.
for (var i = 0; i < num_processes; i++) {
spawn(i);
}
// Helper function for getting a worker index based on IP address.
// This is a hot path so it should be really fast. The way it works
// is by converting the IP address to a number by removing the dots,
// then compressing it to the number of slots we have.
//
// Compared against "real" hashing (from the sticky-session code) and
// "real" IP number conversion, this function is on par in terms of
// worker index distribution only much faster.
var worker_index = function(ip, len) {
var s = '';
for (var i = 0, _len = ip.length; i < _len; i++) {
if (ip[i] !== '.') {
s += ip[i];
}
}
return Number(s) % len;
};
// Create the outside facing server listening on our port.
var server = net.createServer({ pauseOnConnect: true }, function(connection) {
// We received a connection and need to pass it to the appropriate
// worker. Get the worker for this connection's source IP and pass
// it the connection.
var worker = workers[worker_index(connection.remoteAddress, num_processes)];
worker.send('sticky-session:connection', connection);
}).listen(port);
} else {
// Note we don't use a port here because the master listens on it for us.
var app = new express();
// Here you might use middleware, attach routes, etc.
// Don't expose our internal server to the outside.
var server = app.listen(0, 'localhost'),
io = sio(server);
// Tell Socket.IO to use the redis adapter. By default, the redis
// server is assumed to be on localhost:6379. You don't have to
// specify them explicitly unless you want to change them.
io.adapter(sio_redis({ host: 'localhost', port: 6379 }));
// Here you might use Socket.IO middleware for authorization etc.
console.log("Listening");
// Listen to messages sent from the master. Ignore everything else.
process.on('message', function(message, connection) {
if (message !== 'sticky-session:connection') {
return;
}
// Emulate a connection event on the server by emitting the
// event with the connection the master sent us.
server.emit('connection', connection);
connection.resume();
});
}