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Rate limiting API calls - sometimes a Bottleneck is a good thing

Ross Coundon on October 18, 2019

What is Bottleneck and why do I need it in my coding life? If you've spent any time working with 3rd party APIs you'll have come up agai...

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Aroh Sunday • Jun 15 '20

I tried the above suggestion to make multiple requests to a remote third party API to solve the " Socket hangout issue, ECONNRESET in Express.js (Node.js) with multiple requests: but still getting the error. I will appreciate your help. Thanks

Ross Coundon • Jun 15 '20

That means the other end of the connection closed it for some reason. Can you share your code?

Aroh Sunday • Jun 15 '20 • Edited

This is the code I use to simulate the bulk operation

export async function bulkParserSimulator(arrayOfIds) {
  // Fetch CV urls
  // logg.info('Fetching uploaded resume arrays')
  let cvUrl = await getUploadedCVUrl(arrayOfIds);
  let parsedResult = [];
  let save;
  let start = +new Date();
  let parserError;

  // sequential operation
  for (let index = 0, len = cvUrl.length; index < len; index++) {
    const file = cvUrl[index].fileurl;
    const filename = cvUrl[index].filename;
    const jobpositionIdFromArray = cvUrl[index].jobPositionId;
    // Check if cvUrl exist else go to next loop
    if (!file && !filename) continue;

    let singleResult = await throttleApiCall(filename, file);
    console.log({ singleResult });
    const { data } = singleResult;
    if (data.Error) {
      parserError = true;
    }
    if (data.Results) {
      let newparsed = new ParsersCollection(data);
      newparsed.jobPositionId = jobpositionIdFromArray;
      save = await newparsed.save();
      parsedResult.push(save);

      let end = +new Date();
      console.log({ TimeToFinish: end - start + 'ms' });
    }
  }
  // You can return this result then
  let final = { parsedResult, parserError };
  logger.info('Returning the parsed results');
  return final;
}

Then this is the one for bottleneck

import Bottleneck from 'bottleneck';
import { initializeParsingProcess } from './hire';
// Never more than 1 requests running at a time.
// Wait at least 1000ms between each request.
const limiter = new Bottleneck({
  maxConcurrent: 1, // one request per second
  minTime: 333,
});

export const throttleApiCall = limiter.wrap(initializeParsingProcess);

Ross Coundon • Jun 15 '20

How you're wrapping the function looks fine. If you call initializeParsingProcess() directly, what happens?

Aroh Sunday • Jun 15 '20 • Edited

I will get the error below when I call direct. I use bottleneck to see whether that can be solved after going your amazing post here but still getting the same error below

Error: socket hang up
          at createHangUpError (_http_client.js:323:15)
          at TLSSocket.socketOnEnd (_http_client.js:426:23)
          at TLSSocket.emit (events.js:194:15)
          at TLSSocket.EventEmitter.emit (domain.js:441:20)
          at endReadableNT (_stream_readable.js:1125:12)
          at process._tickCallback (internal/process/next_tick.js:63:19)
        code: 'ECONNRESET',

Ross Coundon • Jun 15 '20

Ah, I see, I thought you were suggesting the problem was with your usage of Bottleneck. Can you share the code that you use to call the API?

Paweł Kowalski • Oct 18 '19

Great stuff, thanks for bringing bottleneck to the broader audience.

Raghav Sharma • Jan 23 '21 • Edited

Been using it for quite a while now, it's amazing!