Integralist

Designing Systems and Applications

This is a short document of tips and notes I've accumulated while learning more about designing distributed systems and building concurrent applications. It is by no means definitive and merely scratches the surface of what is needed to be considered when designing an architecture expected to handle large scale traffic.

Distributed Systems

Scale out, not up

There reaches a point in your application's design where by merely throwing more hardware at the problem (i.e. "scaling up") will fail to resolve the scalability issues you're encountering.

phaedryx

Original text here: https://whydavewhy.com/2013/08/16/loyalty-and-layoffs/

dz0ny

[root@arkos ~]# cat /etc/systemd/system/mopidy.service 
[Unit]
Description=Mopidy
After=network.target

[Service]
ExecStart=/usr/bin/mopidy --config=/etc/mopidy.conf

[Install]
WantedBy=multi-user.target

wildlyinaccurate

#!/usr/bin/env sh

##
# This is script with usefull tips taken from:
#   https://github.com/mathiasbynens/dotfiles/blob/master/.osx
#
# install it:
#   curl -sL https://gist.githubusercontent.com/wildlyinaccurate/5539084/raw/hack.sh | sh
#

wildlyinaccurate

# This requires GNU sed (or any sed which supports -i) and expand

find . -type f -printf "sed -i 's/[ \t]*$//' %p && expand -t 4 %p > %p.tmp && mv %p.tmp %p\n" | sh

# It's better to be more specific about which files you want to run the replacement in, e.g.
find . -type f -name *.php -printf "sed -i 's/[ \t]*$//' %p && expand -t 4 %p > %p.tmp && mv %p.tmp %p\n" | sh

# You can use find's -regex option to match multiple extensions (you need to double-escape backslashes in bash):
find . -type f -regex .+\\\.\\\(php\\\|css\\\|js\\\)\$ -printf "sed -i 's/[ \t]*$//' %p && expand -t 4 %p > %p.tmp && mv %p.tmp %p\n" | sh

piscisaureus

Locate the section for your github remote in the .git/config file. It looks like this:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = git@github.com:joyent/node.git

Now add the line fetch = +refs/pull/*/head:refs/remotes/origin/pr/* to this section. Obviously, change the github url to match your project's URL. It ends up looking like this:

erikh

#!/usr/bin/env sh

##
# This is script with usefull tips taken from:
#   https://github.com/mathiasbynens/dotfiles/blob/master/.osx
#
# install it:
#   curl -sL https://raw.github.com/gist/2108403/hack.sh | sh
#

jbgo

UPDATE: A better way! (August 2015)

As pointed out by @johntyree in the comments, using git reflog is easier and more reliable. Thanks for the suggestion!

 $ git reflog
1ed7510 HEAD@{1}: checkout: moving from develop to 1ed7510
3970d09 HEAD@{2}: checkout: moving from b-fix-build to develop
1ed7510 HEAD@{3}: commit: got everything working the way I want
70b3696 HEAD@{4}: commit: upgrade rails, do some refactoring