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

plentz

# to generate your dhparam.pem file, run in the terminal
openssl dhparam -out /etc/nginx/ssl/dhparam.pem 2048

sindresorhus

#!/usr/bin/env bash
# MIT © Sindre Sorhus - sindresorhus.com

# git hook to run a command after `git pull` if a specified file was changed
# Run `chmod +x post-merge` to make it executable then put it into `.git/hooks/`.

changed_files="$(git diff-tree -r --name-only --no-commit-id ORIG_HEAD HEAD)"

check_run() {
	echo "$changed_files" | grep --quiet "$1" && eval "$2"

uhop

user www-data;

http {

  ##
  # Basic Settings
  ##

  sendfile on;
  tcp_nopush on;

listochkin

  --log_gc (Log heap samples on garbage collection for the hp2ps tool.)
        type: bool  default: false
  --expose_gc (expose gc extension)
        type: bool  default: false
  --max_new_space_size (max size of the new generation (in kBytes))
        type: int  default: 0
  --max_old_space_size (max size of the old generation (in Mbytes))
        type: int  default: 0
  --max_executable_size (max size of executable memory (in Mbytes))
        type: int  default: 0

yetithefoot

To enable window.gc() on Chrome browser console you just need to start Chrome like this:

> /Applications/Google\ Chrome.app/Contents/MacOS/Google\ Chrome --js-flags="--expose-gc" --enable-memory-info

Those flags enable the following console API, very usefull to debug memory leaks: 

> console.memory // print memory information
> window.gc() // force garbage collection

kdzwinel

function reloadCSS() {
  const links = document.getElementsByTagName('link');
  
  Array.from(links)
    .filter(link => link.rel.toLowerCase() === 'stylesheet' && link.href)
    .forEach(link => {
      const url = new URL(link.href, location.href);
      url.searchParams.set('forceReload', Date.now());
      link.href = url.href;
    });

paulirish

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

• elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

rauschma

Cheat sheet for callable entities in ES6

Value:

	FD	FE	AF	C	M
Function-callable	✓	✓	✓	×	✓
Constructor-callable	✓	✓	×	✓	×
Prototype	F.p	F.p	F.p	SC	F.p
Property prototype	✓	✓	×	✓	×

jFransham

Achieving warp speed with Rust

Contents:

• Number one optimization tip: don't
• Never optimize blindly
• Don't bother optimizing one-time costs
• Improve your algorithms
• CPU architecture primer
• Keep as much as possible in cache
• Keep as much as possible in registers