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libdispatch efficiency tips

The libdispatch is one of the most misused API due to the way it was presented to us when it was introduced and for many years after that, and due to the confusing documentation and API. This page is a compilation of important things to know if you're going to use this library. Many references are available at the end of this document pointing to comments from Apple's very own libdispatch maintainer (Pierre Habouzit).

My take-aways are:

You should create very few, long-lived, well-defined queues. These queues should be seen as execution contexts in your program (gui, background work, ...) that benefit from executing in parallel. An important thing to note is that if these queues are all active at once, you will get as many threads running. In most apps, you probably do not need to create more than 3 or 4 queues.
Go serial first, and as you find performance bottle necks, measure why, and if concurrency helps, apply with care, always validating under system pressure. Reuse

Stevey's Google Platforms Rant

I was at Amazon for about six and a half years, and now I've been at Google for that long. One thing that struck me immediately about the two companies -- an impression that has been reinforced almost daily -- is that Amazon does everything wrong, and Google does everything right. Sure, it's a sweeping generalization, but a surprisingly accurate one. It's pretty crazy. There are probably a hundred or even two hundred different ways you can compare the two companies, and Google is superior in all but three of them, if I recall correctly. I actually did a spreadsheet at one point but Legal wouldn't let me show it to anyone, even though recruiting loved it.

I mean, just to give you a very brief taste: Amazon's recruiting process is fundamentally flawed by having teams hire for themselves, so their hiring bar is incredibly inconsistent across teams, despite various efforts they've made to level it out. And their operations are a mess; they don't real

Colours in terminal

It's a common confusion about terminal colours... Actually we have this:

plain ascii
ansi escape codes (16 colour codes with bold/italic and background)
256 colour palette (216 colours + 16 ansi + 24 gray) (colors are 24bit)
24bit true colour ("888" colours (aka 16 milion))

printf "\x1b[${bg};2;${red};${green};${blue}m\n"

	/*** MIT LICENSE
	Copyright (c) 2022 torcado

	Permission is hereby granted, free of charge, to any person
	obtaining a copy of this software and associated documentation
	files (the "Software"), to deal in the Software without
	restriction, including without limitation the rights to use,
	copy, modify, merge, publish, distribute, sublicense, and/or sell
	copies of the Software, and to permit persons to whom the
	Software is furnished to do so, subject to the following

	"""
	The most atomic way to train and inference a GPT in pure, dependency-free Python.
	This file is the complete algorithm.
	Everything else is just efficiency.

	@karpathy
	"""

	import os # os.path.exists
	import math # math.log, math.exp

	# OpenClaw Implementation Prompts

	Each prompt below is a self-contained brief you can hand to an AI coding assistant (or use as a project spec) to build that use case from scratch. Adapt the specific services to whatever you already use — the patterns are what matter.

	---

	## 1) Personal CRM Intelligence

	```
	Build me a personal CRM system that automatically tracks everyone I interact with, with smart filtering so it only adds real people — not newsletters, bots, or cold outreach.

	# Applescript to batch OCR PDFs using PDF Expert.
	# By Alex Wellerstein. Last updated December 16, 2024. No copyright asserted -- released for public domain use.
	# Absolutely no warranties, guarantees, promises, ANYTHING provided. Use at your own risk.
	#
	# Will automatically save and close each PDF after OCR completes.
	# Assumes PDF Expert is the default program to open PDFs!
	# Does not have robust error handling. Held together with duct tape.
	# Just a temporary solution until Readdle actually supports batch operations.
	# Seems to work on OS 14.6.1, with PDF Expert 3.10.10.
	# Has not been extensively tested to see what happens if you try to do other work while it is running; could foul up.

	// Run code in Browser Console after enabling chrome debugging --
	// about:config => devtools.chrome.enabled => true
	// https://developer.mozilla.org/docs/Tools/Browser_Console
	try {
	var tabPromise = SyncedTabs._internal.getTabClients();
	tabPromise.then((arrDevices) => {
	if (arrDevices && arrDevices.length > 0){
	// Generate a string with the format of a bookmark export file
	var d, e, out = '<!DOCTYPE NETSCAPE-Bookmark-file-1>\n<META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=UTF-8">\n<TITLE>Bookmarks</TITLE>\n<H1>Bookmarks Menu</H1>\n<DL><p>\n';
	const escapeHtmlEntities = function(aText){return (aText \|\| '').replace(/&/g, '&').replace(/</g, '<').replace(/>/g, '>').replace(/"/g, '"').replace(/'/g, ''')};