hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

caruccio

$ FILE=/some/path/to/file.txt

###################################
### Remove matching suffix pattern
###################################

$ echo ${FILE%.*}          # remove ext 
/some/path/to/file

$ FILE=/some/path/to/file.txt.jpg.gpg    # note various file exts

dergachev

OS X Screencast to animated GIF

This gist shows how to create a GIF screencast using only free OS X tools: QuickTime, ffmpeg, and gifsicle.

Instructions

To capture the video (filesize: 19MB), using the free "QuickTime Player" application:

jimothyGator

mkdir -p /usr/local/etc/nginx/sites-{enabled,available}
cd /usr/local/etc/nginx/sites-enabled
ln -s ../sites-available/default.conf
ln -s ../sites-available/default-ssl.conf

File locations:

• nginx.conf to /usr/local/etc/nginx/
• default.conf and default-ssl.conf to /usr/local/etc/nginx/sites-available
• homebrew.mxcl.nginx.plist to /Library/LaunchDaemons/

willurd

Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000

eito

git filter-branch --commit-filter '
        if [ "$GIT_COMMITTER_NAME" = "<Old Name>" ];
        then
                GIT_COMMITTER_NAME="<New Name>";
                GIT_AUTHOR_NAME="<New Name>";
                GIT_COMMITTER_EMAIL="<New Email>";
                GIT_AUTHOR_EMAIL="<New Email>";
                git commit-tree "$@";
        else
                git commit-tree "$@";

kraftb

#!/bin/bash

BITS=2048

# In one line:
# rm -f temp.key && ssh-keygen -t rsa -b 2048 -f temp.key -N "" -q && ssh-keygen -e -f temp.key -m PKCS8 | tr "\n" " " && echo && cat temp.key | tr "\n" " " && echo

# In multiple lines:
rm -f temp.key
ssh-keygen -t rsa -b $BITS -f temp.key -N "" -q

glebcha

'use strict';

/*
Instructions:

1 - Should execute 'npm run prepare' 
	before the very first run, it will install and symlink all dependencies.

2 - Choose between production 'npm start' and development 'npm run start-dev' modes 
	(watcher will run immediately after initial run).

bramswenson

Amazon SQS Notes

Queue Structure

• Queues are distributed
• Queues are limited to 120000 in-flight messages (use more small queues instead of one large queue)
• Queues may have any number of clients sending/receiving messages at once
• Queues can be created with a built in delay on message visibility
• Queues can be created just for dumping messages whose processing has failed

pnc

Using OTP's observer (appmon replacement) remotely

$ ssh remote-host "epmd -names"
epmd: up and running on port 4369 with data:
name some_node at port 58769

Note the running on port for epmd itself and the port of the node you're interested in debugging. Reconnect to the remote host with these ports forwarded:

$ ssh -L 4369:localhost:4369 -L 58769:localhost:58769 remote-host