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

ericelliott

Most configuration really isn't about the app -- it's about where the app runs, what keys it needs to communicate with third party API's, the db password and username, etc... They're just deployment details -- and there are lots of tools to help manage environment variables -- not the least handy being a simple .env file with all your settings. Simply source the appropriate env before you launch the app in the given env (you could make it part of a launch script, for instance).

env files look like this:

SOMEVAR="somevalue"
ANOTHERVAR="anothervalue"

To source it:

$ source dev.env # or staging.env, or production.env, depending on where you're deploying to

19WAS85

# This is a super **SIMPLE** example of how to create a very basic powershell webserver
# 2019-05-18 UPDATE — Created by me and and evalued by @jakobii and the comunity.

# Http Server
$http = [System.Net.HttpListener]::new() 

# Hostname and port to listen on
$http.Prefixes.Add("http://localhost:8080/")

# Start the Http Server 

dweinstein

# ...
ADD package.json /tmp/package.json
RUN cd /tmp && npm install && \
    mkdir -p /opt/app && cp -a /tmp/node_modules /opt/app/

# ...
WORKDIR /opt/app
ADD . /opt/app

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

isaacs

# Hello, and welcome to makefile basics.
#
# You will learn why `make` is so great, and why, despite its "weird" syntax,
# it is actually a highly expressive, efficient, and powerful way to build
# programs.
#
# Once you're done here, go to
# http://www.gnu.org/software/make/manual/make.html
# to learn SOOOO much more.

arturmkrtchyan

|----------------------------------------------------------------------------------------|--------------------|
|                                    Object Header (64 bits)                             |        State       |
|-------------------------------------------------------|--------------------------------|--------------------|
|                  Mark Word (32 bits)                  |      Klass Word (32 bits)      |                    |
|-------------------------------------------------------|--------------------------------|--------------------|
| identity_hashcode:25 | age:4 | biased_lock:1 | lock:2 |      OOP to metadata object    |       Normal       |
|-------------------------------------------------------|--------------------------------|--------------------|
|  thread:23 | epoch:2 | age:4 | biased_lock:1 | lock:2 |      OOP to metadata object    |       Biased       |
|-------------------------------------------------------|--------------------------------|--------------------|
|               

makeittotop

Out of Memory (OOM) refers to a computing state where all available memory, including swap space, has been allocated.

Normally this will cause the system to panic and stop functioning as expected.
There is a switch that controls OOM behavior in /proc/sys/vm/panic_on_oom. 
When set to 1 the kernel will panic on OOM. 
A setting of 0 instructs the kernel to call a function named oom_killer on an OOM.
Usually, oom_killer can kill rogue processes and the system will survive. 
The easiest way to change this is to echo the new value to /proc/sys/vm/panic_on_oom.

# cat /proc/sys/vm/panic_on_oom 1

arganzheng

package org.opentsdb.client;

import static com.google.common.base.Preconditions.checkArgument;

import java.io.IOException;
import java.util.concurrent.TimeUnit;

import org.apache.commons.lang.StringUtils;
import org.apache.http.HeaderElement;
import org.apache.http.HeaderElementIterator;

straker

/**
 * @param {object} scope - Object that all bound data will be attached to.
 */
function twoWayBind(scope) {
  // a list of all bindings used in the DOM
  // @example
  // { 'person.name': [<input type="text" data-bind="person.name"/>] }
  var bindings = {};

  // each bindings old value to be compared for changes