Throttle and queue up API requests due to per second cap

For an alternative solution, I used the node-rate-limiter to wrap the request function like this:

var request = require('request');
var RateLimiter = require('limiter').RateLimiter;

var limiter = new RateLimiter(1, 100); // at most 1 request every 100 ms
var throttledRequest = function() {
    var requestArgs = arguments;
    limiter.removeTokens(1, function() {
        request.apply(this, requestArgs);
    });
};

The npm package simple-rate-limiter seems to be a very good solution to this problem.

Moreover, it is easier to use than node-rate-limiter and async.queue.

Here's a snippet that shows how to limit all requests to ten per second.

var limit = require("simple-rate-limiter");
var request = limit(require("request")).to(10).per(1000);

I've run into the same issue with various APIs. AWS is famous for throttling as well.

A couple of approaches can be used. You mentioned async.map() function. Have you tried async.queue()? The queue method should allow you to set a solid limit (like 6) and anything over that amount will be placed in the queue.

Another helpful tool is oibackoff. That library will allow you to backoff your request if you get an error back from the server and try again.

It can be useful to wrap the two libraries to make sure both your bases are covered: async.queue to ensure you don't go over the limit, and oibackoff to ensure you get another shot at getting your request in if the server tells you there was an error.