深度嵌套的异步请求未执行。需要帮助修复或调试建议

Question

我正在 node.js 中编写缓存预热脚本。它同时使用 Async 和 Request npm 模块。示例代码中唯一真正的变化是变量名称和值。

var languages = ['es', 'en'];
var baseUrl = 'http://localhost:8080/';
var presents = [1,2,3,4];
var foods = ['green eggs', 'roast beast', 'potatas'];

async.each(languages, function (lang, callback) {

    async.each(whos, function (who, callback2) {

        request.get(baseUrl + lang + '/' + who, function (err, res, body) {
            var grinches = body;

            async.each(grinches, function (grinch, callback3) {

                    async.each(presents, function (present, callback4) {

                        async.each(foods, function (food, callback5) {
                            var finalUrl = baseUrl + lang + '/comp/' + who + '/' + grinch + '/' + present + '/' + food;

                            console.log(finalUrl);
                            request.get(baseUrl + 'en/ac', function (error, response, body) {
                                console.log(error);
                                console.log(response);
                                console.log(body);
                                callback5();
                            });
                        }, function () {
                            callback4();
                        });

                    }, function () {
                        callback3();
                    });

                });
            }, function () {
                callback2();
            });

        });
    }, function () {
        callback();
    });

}, function () {
    cb(null, 7);
});

在此示例中，finalUrl 成功记录，但紧随其后的请求中的任何内容都不会记录。如果我抓取其中一个 finalUrl 并将其放入浏览器中，请求将得到正确处理。异步或请求中是否存在我可能遇到的某种堆栈限制？

如果我不是在那个点发出请求，而是将 url 推入一个数组，然后遍历它以从最终的 async.each 回调中发出请求，它们将起作用。但是，此解决方案存在性能（内存）问题，因为我必须维护大量快速增长的数组。这是该解决方案的示例

var languages = ['es', 'en'];
var baseUrl = 'http://localhost:8080/';
var presents = [1,2,3,4];
var foods = ['green eggs', 'roast beast', 'potatas'];
var urls = [];

async.each(languages, function (lang, callback) {

    async.each(whos, function (who, callback2) {

        request.get(baseUrl + lang + '/' + who, function (err, res, body) {
            var grinches = body;

            async.each(grinches, function (grinch, callback3) {

                    async.each(presents, function (present, callback4) {

                        async.each(foods, function (food, callback5) {
                            var finalUrl = baseUrl + lang + '/comp/' + who + '/' + grinch + '/' + present + '/' + food;

                            urls.push(finalUrl);
                        }, function () {
                            callback4();
                        });

                    }, function () {
                        callback3();
                    });

                });
            }, function () {
                callback2();
            });

        });
    }, function () {
        callback();
    });

}, function () {
    for (var i = 0; i < urls.length; i++) {
        request.get(urls[i], function (err, res, body) {
            console.log('this works');
        })
    }
});

我还可以尝试什么？

Answer 1

使用 async.each will execute all the tasks in parallel, this might cause some performance issues specially when there are a lot of tasks in the tasks array, as a work around "though it might be slower in execution!" you might want to use async.eachSeries 确保您的所有任务运行 一个接一个 而不是并行执行。

深度嵌套的异步请求未执行。需要帮助修复或调试建议

Deeply nested async request is not executing. Need help fixing or with debugging suggestions

asynchronous

request

node.js