How to do parallel async multiple requests at once

问题:

Array and loops through but I want to be able to run all of them in parallel instead as I don't want to run one after another.

I basically want to store all endpoint calls status codes, body and time as array and return them as results regardless of there are errors or not in the endpoint.

I'm using Bluebird, how can I use its features to solve this issue?

回答1:

You can use Promise.map with .bind:

function getComponentStatuses(componentsToCheck) {
    return Promise.map(componentsToCheck, function() {
        var start = Date.now();
        return getAsync({
            url: component.endpoint,
            timeout: component.timeout
        })
        .bind({
             name: component.name,
             status: null,
             body: null,
             time: null
        })
        .spread(function(response, body){
            Logger.info('GET took ' + end + 'ms.');
            this.status = response.statusCode;
            this.body = body;
            return this;
        })
        .catch(function(e) { return this; })
        .finally(function() { this.time = Date.now() - start; })
    });
}

Note that your timing method is incorrect because the http agent might throttle requests.

回答2:

Bluebird supports multiple concurrent Promises.

See the reference at: https://github.com/petkaantonov/bluebird/blob/master/API.md#promisejoinpromisethenablevalue-promises-function-handler---promise

There are two ways to do it:

.all() - good for a dynamic number of promises

.join() - good for a fixed number of promises and as for Bluebird's documentation, it supplies a better performance than .all() method.

From bluebird's documentation:

 var Promise = require("bluebird");
 var join = Promise.join;

join(getPictures(), getComments(), getTweets(),
function(pictures, comments, tweets) {
console.log("in total: " + pictures.length + comments.length + tweets.length);
});

回答3:

Found the solution.

Use .settle

回答4:

I use q Promise Maybe help

return q.all([function or value1, function or value 2, ......])
.spread(function (result1, result2, ....) {
   // do somethine
})

............