NodeJS的Cluster模块使用

一.前言
大家都知道nodejs是一个单进程单线程的服务器引擎,不管有多么的强大硬件,只能利用到单个CPU进行计算。所以,有人开发了第三方的cluster,让node可以利用多核CPU实现并行。

随着nodejs的发展,让nodejs上生产环境,就必须是支持多进程多核处理!在V0.6.0版本,Nodejs内置了cluster的特性。自此,Nodejs终于可以作为一个独立的应用开发解决方案,映入大家眼帘了。

最简单的例子:

var cluster = require('cluster');
var http = require('http');
var numCPUs = require('os').cpus().length; if (cluster.isMaster) {
console.log("master start..."); // Fork workers.
for (var i = 0; i < numCPUs; i++) {
cluster.fork();
} cluster.on('listening',function(worker,address){
console.log('listening: worker ' + worker.process.pid +', Address: '+address.address+":"+address.port);
}); cluster.on('exit', function(worker, code, signal) {
console.log('worker ' + worker.process.pid + ' died');
});
} else {
http.createServer(function(req, res) {
res.writeHead(200);
res.end("hello world\n");
}).listen(0);
}

二.cluster的工作原理

每个worker进程通过使用child_process.fork()函数,基于IPC(Inter-Process Communication,进程间通信),实现与master进程间通信。

当worker使用server.listen(...)函数时 ,将参数序列传递给master进程。如果master进程已经匹配workers,会将传递句柄给工人。如果master没有匹配好worker,那么会创建一个worker,再传递并句柄传递给worker。

在边界条件,有3个有趣的行为:
注:下面server.listen(),是对底层“http.Server-->net.Server”类的调用。

  • 1. server.listen({fd: 7}):在master和worker通信过程,通过传递文件,master会监听“文件描述为7”,而不是传递“文件描述为7”的引用。
  • 2. server.listen(handle):master和worker通信过程,通过handle函数进行通信,而不用进程联系
  • 3. server.listen(0):在master和worker通信过程,集群中的worker会打开一个随机端口共用,通过socket通信,像上例中的57132

当多个进程都在 accept() 同样的资源的时候,操作系统的负载均衡非常高效。Node.js没有路由逻辑,worker之间没有共享状态。所以,程序要设计得简单一些,比如基于内存的session。

因为workers都是独力运行的,根据程序的需要,它们可以被独立删除或者重启,worker并不相互影响。只要还有workers存活,则master将继续接收连接。Node不会自动维护workers的数目。我们可以建立自己的连接池。

三. cluster的API

官网地址:http://nodejs.org/api/cluster.html#cluster_cluster

cluster对象
cluster的各种属性和函数

cluster.setttings:配置集群参数对象
cluster.isMaster:判断是不是master节点
cluster.isWorker:判断是不是worker节点
Event: 'fork': 监听创建worker进程事件
Event: 'online': 监听worker创建成功事件
Event: 'listening': 监听worker向master状态事件
Event: 'disconnect': 监听worker断线事件
Event: 'exit': 监听worker退出事件
Event: 'setup': 监听setupMaster事件
cluster.setupMaster([settings]): 设置集群参数
cluster.fork([env]): 创建worker进程
cluster.disconnect([callback]): 关闭worket进程
cluster.worker: 获得当前的worker对象
cluster.workers: 获得集群中所有存活的worker对象
worker对象
worker的各种属性和函数:可以通过cluster.workers, cluster.worket获得。

worker.id: 进程ID号
worker.process: ChildProcess对象
worker.suicide: 在disconnect()后,判断worker是否自杀
worker.send(message, [sendHandle]): master给worker发送消息。注:worker给发master发送消息要用process.send(message)
worker.kill([signal='SIGTERM']): 杀死指定的worker,别名destory()
worker.disconnect(): 断开worker连接,让worker自杀
Event: 'message': 监听master和worker的message事件
Event: 'online': 监听指定的worker创建成功事件
Event: 'listening': 监听master向worker状态事件
Event: 'disconnect': 监听worker断线事件
Event: 'exit': 监听worker退出事件

四.master和worker的通信

var cluster = require('cluster');
var http = require('http');
var numCPUs = require('os').cpus().length; if (cluster.isMaster) {
console.log('[master] ' + "start master..."); for (var i = 0; i < numCPUs; i++) {
var wk = cluster.fork();
wk.send('[master] ' + 'hi worker' + wk.id);
} cluster.on('fork', function (worker) {
console.log('[master] ' + 'fork: worker' + worker.id);
}); cluster.on('online', function (worker) {
console.log('[master] ' + 'online: worker' + worker.id);
}); cluster.on('listening', function (worker, address) {
console.log('[master] ' + 'listening: worker' + worker.id + ',pid:' + worker.process.pid + ', Address:' + address.address + ":" + address.port);
}); cluster.on('disconnect', function (worker) {
console.log('[master] ' + 'disconnect: worker' + worker.id);
}); cluster.on('exit', function (worker, code, signal) {
console.log('[master] ' + 'exit worker' + worker.id + ' died');
}); function eachWorker(callback) {
for (var id in cluster.workers) {
callback(cluster.workers[id]);
}
} setTimeout(function () {
eachWorker(function (worker) {
worker.send('[master] ' + 'send message to worker' + worker.id);
});
}, 3000); Object.keys(cluster.workers).forEach(function(id) {
cluster.workers[id].on('message', function(msg){
console.log('[master] ' + 'message ' + msg);
});
}); } else if (cluster.isWorker) {
console.log('[worker] ' + "start worker ..." + cluster.worker.id); process.on('message', function(msg) {
console.log('[worker] '+msg);
process.send('[worker] worker'+cluster.worker.id+' received!');
}); http.createServer(function (req, res) {
res.writeHead(200, {"content-type": "text/html"});
res.end('worker'+cluster.worker.id+',PID:'+process.pid);
}).listen(3000); }

五.从Redis队列中取数据,并将其写入到Mysql中

var cluster = require('cluster');
var http = require('http');
var numCPUs = require('os').cpus().length; var queueHost = '192.168.235.60';
var queuePort = 6379; var dataConnection = {};
dataConnection.host = 'localhost';
dataConnection.user = 'root';
dataConnection.password = '';
dataConnection.database = 'livedb'; if (cluster.isMaster) {
for (var i = 0; i < numCPUs; i++) {
cluster.fork();
} cluster.on('fork', function (worker) {
console.log('[master] Create worker. pid: '+worker.process.pid);
}); cluster.on('online', function (worker) {
console.log('[master] Worker online. pid: ' +worker.process.pid);
}); cluster.on('disconnect', function (worker) {
console.log('[master] ' + 'disconnect: worker: ' + worker.process.pid);
}); cluster.on('exit', function (worker, code, signal) {
console.log('[master] ' + 'exit worker: ' + worker.process.pid + ' died');
}); function eachWorker(callback) {
for (var id in cluster.workers) {
callback(cluster.workers[id]);
}
} /*
//send to child
setTimeout(function () {
eachWorker(function (worker) {
worker.send('[master] ' + 'send message to worker' + worker.id);
});
}, 3000);
*/ Object.keys(cluster.workers).forEach(function(id) {
cluster.workers[id].on('message', function(message){
if(message.act === 'suicide'){
//cluster.fork();
}
});
}); }
else if (cluster.isWorker) {
process.on('message', function(msg) {
//send to parent
//process.send('[worker] worker'+cluster.worker.id+' received!');
}); var redis = require("redis"),
client = redis.createClient(queuePort, queueHost);
client.on("error", function (err){
console.log("[process] Error " + err);
}); var mysql = require('mysql');
var connection = mysql.createConnection(dataConnection);
connection.connect(); process.on('uncaughtException', function(err){
console.log("[process] UncaughtException: " + err);
connection.end();
process.send({act:'suicide'});
process.exit(1);
}); setInterval(function(){
client.rpop("message",function (err,value){
if(value!=null){
//console.log("[process] Handler" + process.pid + ": " + value); var obj = JSON.parse(value);
var account = {accountid: obj.time, openid: obj.stamp};
console.log(account); var query = connection.query('INSERT INTO pre_qqaccount SET ?', account, function(err, result) {
if(err){
console.log('[process] insert database error: '+err);
}
});
}
});
},1000);
}
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