Ben Grunfeld bengrunfeld

Concurrent Requests in Node.js (Javascript) using Async/Await

To make concurrent asynchronous requests in NodeJS (Javascript), we can take advantage of the setTimeout function and use it together with async/await, plus trusty old count.

What we are aiming for here is that 3 requests get sent asynchronously, but the promise they're contained in only resolves when ALL 3 have returned. If it takes too long, we want to reject the promise, since the data has likely become stale.

Originally I tried using Promise.all(), but ran into problems with it. The following implementation worked

	def make_ndb_return_data_json_serializable(data):
	"""Build a new dict so that the data can be JSON serializable"""

	result = data.to_dict()
	record = {}

	# Populate the new dict with JSON serializiable values
	for key in result.iterkeys():
	if isinstance(result[key], datetime.datetime):
	record[key] = result[key].isoformat()

	"""
	Sometimes you need to forcefully set headers in Webapp2 while using Google App Engine (GAE).
	It is NOT RECOMMENDED to use `*` for `Access-Control-Allow-Origin` as below. I've put it
	there simply for the sake of demonstration. Make sure you choose something more restrictive.
	"""

	def initialize_headers(headers, http_verb):
	"""Set up the headers for HTTP requests"""

	headers['Access-Control-Allow-Origin'] = '*'

	" Use spaces instead of tabs. Use 4 spaces when User presses the tab button. Display line numbers
	set expandtab tabstop=4 shiftwidth=4 softtabstop=4 number
	retab

	" Syntax highlighting
	syntax on

	" Color any column past 79 chars for Python PEP-8 compliance
	set colorcolumn=80

	# Gunicorn Shortcuts
	alias p='pstree -ap\|grep gunicorn'
	alias k='kill -HUP'

	# New with Ubuntu 14.04 LTS update, I think
	alias c='sudo cp -r /home/vagrant/tetralytics/src/static/dist /home/vagrant/tt-server/src/static/;
	sudo cp -r /home/vagrant/tetralytics/src/templates /home/vagrant/tt-server/src'

	BEST COINS FOR ARBITRAGE:

	1. Verge
	Low: BTC 0.00001100
	High: BTC 0.00001600
	Profit: 45%

	2. Tron
	Low: BTC 0.00000250
	High: BTC 0.00000315


	<!doctype html>
	<html lang="en-US">
	<head>
	<meta charset="utf-8">
	<meta http-equiv="x-ua-compatible" content="ie=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>credible – Just another WordPress site</title>
	<link rel='dns-prefetch' href='//fonts.googleapis.com' />
	<link rel='dns-prefetch' href='//s.w.org' />

	const c1 = target => {
	const pre = 'https://www.binance.com/tradeDetail.html?symbol='
	window.open(`${pre}${target}_BTC`, '_blank')
	}

	const c2 = target => {
	const pre = 'https://www.binance.com/tradeDetail.html?symbol='
	window.open(`${pre}${target}_ETH`, '_blank')
	}

	# From Stack Overflow question: "AWS Elastic Beanstalk with ALB: Node Websocket times out"

	-------------------------------------
	/var/log/nodejs/nodejs.log
	-------------------------------------
	> [email protected] start /var/app/current
	> node ./dist/server.js

	Prod: App listening to 8081....
	Press Ctrl+C to quit.

	const sayHello = () =>
	console.log('Hello, World')

	sayHello()