节点js套接字解释

Question

我正在构建一个应用程序,它将对远程api服务器进行大约一百万次调用.我是否可以限制连接数量,例如10？我将max套接字设置为10会这样做吗？

我试图了解这些参数的作用:

keepAlive: false,
maxSockets: 999,
maxFreeSockets: 1

在节点http get函数中,在以下代码中:

var inputData = [];

for(i=1; i<=5000;i++){
    inputData.push('number' + i);
}

var options = {
    host: "localhost",
    port: 80,
    path: "/text.txt",
    keepAlive: false,
    maxSockets: 999,
    maxFreeSockets: 1
}


var limit = inputData.length;
var counter = 0;

function fetchData(number){

    return new Promise(function(resolve, reject){
        var http = require('http');

        fetch  = function(resp){
            var body = '';
            resp.on('data',function(chunk){
                body += chunk;
            })
            resp.on('end',function(){
                console.log(resp)
                resolve()
            })
            resp.on('error',function(err){
                console.log('error');
            })
        }
        var req = http.request(options, fetch);

        req.end();

    })
}



Promise.all(inputData.map(number => fetchData(number))).then(function(results) {
    console.log('finished');
    connection.end();

})
.catch(function(error) {
    console.log('there wa an error');
    console.log(error);
});

Answer 1

你真的不想发起1,000,000个请求,并且不知何故希望maxSockets一次管理100个请求.有很多原因导致这不是一个很好的做事方式.相反,您应该使用自己的代码来管理一次100个实时连接的数量.

有很多方法可以做到这一点:

1. 编写自己的代码,激活100,然后每次完成,它会激活下一个.

2. 使用Promise.map()具有内置并发功能的Bluebird ,它将同时管理多少个飞行时间.

3. 使用async.mapLimit()具有内置并发功能的Async ,它将同时管理有多少是空中飞行.

至于自己编写代码来做这件事,你可以做这样的事情;

function fetchAll() {
    var start = 1;
    var end = 1000000;
    var concurrentMax = 100;
    var concurrentCnt = 0;
    var cntr = start;
    return new Promise(function(resolve, reject) {

        // start up requests until the max concurrent requests are going
        function run() {
            while (cntr < end && concurrentCnt < concurrentMax) {
                ++concurrentCnt;
                fetchData(cntr++).then(function() {
                    --concurrentCnt;
                    run();
                }, function(err) {
                    --concurrentCnt;
                    // decide what to do with error here
                    // to continue processing more requests, call run() here
                    // to stop processing more requests, call reject(err) here
                });
            }
            if (cntr >= end && concurrentCnt === 0) {
                // all requests are done here
                resolve();
            }        
        }

        run();
    });

}