Script to trigger lambda throttling. Creates many concurrent lambda calls to a long-running function.

lambda-functionWhileThrottled.js

// just a control; doesn't matter specifics
exports.handler = function(event, context) {
    console.log('starting');
    setTimeout(function() {
        console.log('done');
        context.succeed();
    }, 1000);
};

lambda-slowFunctionTest.js

// succeeds after 5m
exports.handler = function(event, context) {
    console.log('starting');
    setTimeout(function() {
        console.log('done');
        context.succeed();
    }, 300000);
};

testing-aws-lambda-concurrency-limts.js

'use strict';

// expects your aws key/secret to be in env
// and both async & aws-sdk installed

// calls the target lambda function with parallelLimit N times; logs results

// 1. create two lambda functions slowFunctionTest (5m execution duration) and functionWhileThrottled (whatever)
// 2. run ~500 iterations on slowFunctionTest with Event invocation; all should return http 202
// 3. check console to ensure throttling is in effect
// 4. change target function to functionWhileThrottled and RequestResponse invocation and run ~20 iterations
// 5. will likely show "Rate Limited" errors (http 429)

var async = require('async');
var AWS = require('aws-sdk');
var lambda = new AWS.Lambda({ region: 'us-east-1' });

var tasks = [];

for (var i=0; i < 5; i++) {
  (function(index) {
    tasks.push(function(taskCallback) {
      console.log('Invoking', index);
      lambda.invoke({
        // FunctionName: 'slowFunctionTest',
        // InvocationType: 'Event',
        FunctionName: 'functionWhileThrottled',
        InvocationType: 'RequestResponse',
        LogType: 'None',
        Payload: ''
      }, function(err, res) {
        if (err) {
          taskCallback(null, { index: index, response: err.message });
        }
        else {
          taskCallback(null, { index: index, response: res.StatusCode });
        }
      });
    });
  })(i);
}

async.parallelLimit(tasks, 8, console.log.bind(console));