Ricardo Ander-Egg polyrand

Virtual Hosts on nginx (CSC309)

When hosting our web applications, we often have one public IP address (i.e., an IP address visible to the outside world) using which we want to host multiple web apps. For example, one may wants to host three different web apps respectively for example1.com, example2.com, and example1.com/images on the same machine using a single IP address.

How can we do that? Well, the good news is Internet browsers

Easy parallel python with concurrent.futures

As of version 3.3, python includes the very promising concurrent.futures module, with elegant context managers for running tasks concurrently. Thanks to the simple and consistent interface you can use both threads and processes with minimal effort.

For most CPU bound tasks - anything that is heavy number crunching - you want your program to use all the CPUs in your PC. The simplest way to get a CPU bound task to run in parallel is to use the ProcessPoolExecutor, which will create enough sub-processes to keep all your CPUs busy.

We use the context manager thusly:

with concurrent.futures.ProcessPoolExecutor() as executor:

Note: I'm currently taking a break from this course to focus on my studies so I can finally graduate

	# Add the following 'help' target to your Makefile
	# And add help text after each target name starting with '\#\#'

	help: ## Show this help.
	@fgrep -h "##" $(MAKEFILE_LIST) \| fgrep -v fgrep \| sed -e 's/\\$$//' \| sed -e 's/##//'

	# Everything below is an example

	target00: ## This message will show up when typing 'make help'
	@echo does nothing

	#!/bin/bash

	# This script assumes you have an app running on 2 ports 4040 and 4041
	# and that you can restart your app with a single command

	APP_RESTART_COMMAND="/your/app/control restart"

	# Find out if the app is running
	function app_up {
	port=$1

	-- Remove the history from
	rm -rf .git

	-- recreate the repos from the current content only
	git init
	git add .
	git commit -m "Initial commit"

	-- push to the github remote repos ensuring you overwrite history
	git remote add origin [email protected]:<YOUR ACCOUNT>/<YOUR REPOS>.git

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD

Ricardo Ander-Egg polyrand

Virtual Hosts on nginx (CSC309)

Easy parallel python with concurrent.futures

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