jboner

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

stephenhardy

-- 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 git@github.com:<YOUR ACCOUNT>/<YOUR REPOS>.git

dideler

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

Table of Contents

1. Overview
2. Introduction
3. Interactive Start
4. Linux and Server-Side Javascript
5. Linux Command Line
6. Linux Development Environment

anfleene

#!/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

prwhite

# 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

mangecoeur

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:

soheilhy

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

rabbitt

import psycopg2 as pg

from io import BytesIO
from collections import defaultdict
from contextlib import contextmanager
from psycopg2.extensions import ISOLATION_LEVEL_AUTOCOMMIT, ISOLATION_LEVEL_READ_COMMITTED

READ_COMMIT = ISOLATION_LEVEL_READ_COMMITTED
AUTO_COMMIT = ISOLATION_LEVEL_AUTOCOMMIT

mwender

#import <Foundation/Foundation.h>
#import <Cocoa/Cocoa.h>
#import <unistd.h>
BOOL copy_to_clipboard(NSString *path)
{
  // http://stackoverflow.com/questions/2681630/how-to-read-png-image-to-nsimage
  NSImage * image;
  if([path isEqualToString:@"-"])
  {
    // http://caiustheory.com/read-standard-input-using-objective-c 

drmalex07

README

Create a template service file at /etc/systemd/system/secure-tunnel@.service. The template parameter will correspond to the name of target host:

[Unit]
Description=Setup a secure tunnel to %I
After=network.target