Saswata Dutta saswata-dutta

My AWS Cloud9 Setup for Python/Django and Node

Getting setup

sudo yum -y update

I'm not a big fan of their default bash prompt:

echo "export PS1='[\D{%F %T}]\n\[\e]0;\w\a\]\[\e[32m\]\u:\[\e[33m\]\w\[\e[0m\]\n\$ '" >> ~/.bashrc

source ~/.bashrc

(In Ktor: 1.6.2)

application.conf

...
jwt {
    issuer = "https://cognito-idp.ap-northeast-1.amazonaws.com/__SPECIFY_POOL_ID_HERE__"
    audience = "__SPECIFY_CLIENT_ID_HERE__"
    realm = "ktor sample app"

How to get a stack trace for each thread in a running Python script

Sometimes a Python script will simply hang forever with no indication of what is going wrong. Perhaps it's polling a service that will never return a value that allows the program to move forward.

Here's a way to see where the program is currently stuck, using pyrasite a tool for injecting code into running Python processes.

Install gdb and pyrasite

Install gdb.

	# This Source Code Form is subject to the terms of the Mozilla Public
	# License, v. 2.0. If a copy of the MPL was not distributed with this
	# file, You can obtain one at https://mozilla.org/MPL/2.0/.

	# Context: https://stackoverflow.com/a/56701174/149900

	from io import StringIO


	WHITESPACE = " \t\r\n"

	import sys

	# choose() is the same as computing the number of combinations. Normally this is
	# equal to:
	#
	# factorial(N) / (factorial(m) * factorial(N - m))
	#
	# but this is very slow to run and requires a deep stack (without tail
	# recursion).
	#

	from PIL import Image
	from PIL.ExifTags import TAGS, GPSTAGS

	def get_exif_data(image):
	"""Returns a dictionary from the exif data of an PIL Image item. Also converts the GPS Tags"""
	exif_data = {}
	info = image._getexif()
	if info:
	for tag, value in info.items():
	decoded = TAGS.get(tag, tag)

	config:
	target: "http://localhost:8000"
	http:
	timeout: 10 # Responses have to be sent within 10 seconds or the request will be aborted
	processor: "./processor.js"

	phases:
	# Create 100 virtual users every second for 60 seconds
	- duration: 60 # seconds
	arrivalRate: 100 # virtual users

	"""
	Simple worker showing different worker ids sharing/incrementing the same memory region
	uwsgi --http :9090 --wsgi-file foobar.py --master --processes 4 --threads 2 --stats 127.0.0.1:9191 --sharedarea 2
	Then just keep refreshing localhost:9090
	"""

	import uwsgi

	INT_ORDS = {48, 49, 50, 51, 52, 53, 54, 55, 56, 57}

	# Credit for this: Nicholas Swift
	# as found at https://medium.com/@nicholas.w.swift/easy-a-star-pathfinding-7e6689c7f7b2
	from warnings import warn
	import heapq

	class Node:
	"""
	A node class for A* Pathfinding
	"""