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async和await

Async/Await应该是最简单的异步解决方案了。举个例子,写个暂停功能:

var sleep = function (time) {
    return new Promise(function (resolve, reject) {
        setTimeout(function () {
            resolve();
        }, time);
    })
};

var start = async function () {
    // 看起来就像同步代码
    console.log('start');
    await sleep(3000);
    console.log('end');
};

start();

控制台先输出start,稍等3秒后,输出了end。

代码

/**
 * Created by salamander on 2016/9/21.
 */
let request = require('request');
let url = "http://localhost/index.php";
let concurrency = 100;

function testLocal() {
    return new Promise((resolve, reject) => {
        request(url, function (error, response, body) {
            if (!error && response.statusCode == 200) {
                resolve();
            } else {
                reject(error);
            }
        });
    });
}


async function testConcurrency() {
    for(let i = 0; i < 100; i++) {
        try {
            let tasks = [];
            for(let j = 0; j < concurrency; j++) {
                tasks.push(testLocal())
            }
            await Promise.all(tasks);
            console.log('request success ' + i);
        } catch(error) {
            console.log('request failed');
        }
    }
}

testConcurrency();

说明

concurrency量可以设置并发请求次数

测试

clipboard.png


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