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

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

jlsherrill

Shut down foreman-tasks:

  service foreman-tasks stop

Open the rails console:

foreman-rake console

subfuzion

Common Options

-#, --progress-bar Make curl display a simple progress bar instead of the more informational standard meter.

-b, --cookie <name=data> Supply cookie with request. If no =, then specifies the cookie file to use (see -c).

-c, --cookie-jar <file name> File to save response cookies to.

citrusui

How do I dropdown?

This is how you dropdown.

<details>
<summary>How do I dropdown?</summary>
<br>
This is how you dropdown.

albertorestifo

  componentDidUpdate(prevProps) {
    console.log('Rrow update diff:');

    const now = Object.entries(this.props);
    const added = now.filter(([key, val]) => {
      if (prevProps[key] === undefined) return true;
      if (prevProps[key] !== val) {
        console.log(`${key}
          - ${JSON.stringify(val)}

jlsherrill

Using minitest-bisect to debug tranient test failures

When to use?

1. You have a test that is failing occasionally locally or in jenkins
2. It doesn't fail when you run just one test, it requires the entire test suite to run

How to use minitest-bisect

Note that many of these instructions will be katello specific, but will work with slight modifications for foreman or other rails projects.

1. Find a failing seed number

pierrejoubert73

How to add a collapsible section in markdown

1. Example

Click me

Heading

1. Foo
2. Bar
   • Baz

• Qux

johnpapa

Docker - How to cleanup (unused) resources

Cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

sorenlouv

import React, { Component } from 'react';

export default function withPropsChecker(WrappedComponent) {
  return class PropsChecker extends Component {
    componentWillReceiveProps(nextProps) {
      Object.keys(nextProps)
        .filter(key => {
          return nextProps[key] !== this.props[key];
        })
        .map(key => {