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Latency numbers every frontend developer should know

Originally published by Malte Ubl at https://vercel.com/blog/latency-numbers-every-web-developer-should-know.

Metric	Estimate	Metric Impact	Comments
Wifi latency to internet	1-4ms	TTFB, FCP, LCP	Wifi adds minimal latency to a connection. This can increase with a weak signal or older hardware.
5G high-band (millimeter wave) latency to internet	1-5ms	TTFB, FCP, LCP	Millimeter wave is the fastest deployed mobile technology. However, it is only practical to use in dense urban areas with a line of sight to the radio tower.
User-space budget per frame for 60 frames per second	5-10ms	Smooth framerate	On a 60fps device, a frame is painted every 16ms. However

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Building a test setup for load testing with Tsung

Originally published by Emre Bastuz at https://hml.io/2015/08/04/loadtesting-with-tsung-and-multiple-ips/.

Overview

From time to time it is necessary to create multiple network sessions in a testing environment, to see how a component handles those sessions.

The following description will show a testing setup to create multiple TCP sessions by using a combination of techniques:

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Palette

A tiny python script to extract color palettes from any image.

Original script available in rebelot/kanagawa.nvim.

Usage

$ python palette.py --help

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rm *.pem
rm *.srl
rm *.cnf

# 1. Generate CA's private key and self-signed certificate
openssl req -x509 -newkey rsa:4096 -days 365 -nodes -keyout ca-key.pem -out ca-cert.pem -subj "/C=FR/ST=Occitanie/L=Toulouse/O=Test Org/OU=Test/CN=*.test/emailAddress=test@gmail.com"

echo "CA's self-signed certificate"
openssl x509 -in ca-cert.pem -noout -text

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Setup multiple git identities & git user informations

/!\ Be very carrefull in your setup : any misconfiguration make all the git config to fail silently ! Go trought this guide step by step and it should be fine 😉

Setup multiple git ssh identities for git

• Generate your SSH keys as per your git provider documentation.
• Add each public SSH keys to your git providers acounts.
• In your ~/.ssh/config, set each ssh key for each repository as in this exemple:

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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

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Publishing Golang application on GitHub

• Makefile
• Dockerfile
• Github Actions
• Goreleaser

Makefile

• requires Git tags

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Performance Reading

Tinkoff

• Материалы для подготовки к собеседованию:
  • Секция по дизайну проектов тестирования производительности

Yandex

• Yandex.Tank wiki:

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Keybase proof

I hereby claim:

• I am aliesbelik on github.
• I am veslefrik (https://keybase.io/veslefrik) on keybase.
• I have a public key ASAPPXhZTP5qs5wwaZJ4xYEoGMNZ8Rt0YvMAewQ0MaT3wwo

To claim this, I am signing this object:

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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