Dmitry Chuev sleepy-cat

FAQ on the xz-utils backdoor (CVE-2024-3094)

This is a living document. Everything in this document is made in good faith of being accurate, but like I just said; we don't yet know everything about what's going on.

Update: I've disabled comments as of 2025-01-26 to avoid everyone having notifications for something a year on if someone wants to suggest a correction. Folks are free to email to suggest corrections still, of course.

Background

High Performance Redis

In response to this brief blog entry, @antirez tweeted for some documentation on high-performance techniques for Redis. What I present here are general high-performance computing (HPC) techniques. The examples are oriented to Redis. but they work well for any program designed to be single- or worker-threaded and asynchronous (e.g. uses epoll).

The motivation for using these techniques is to maximize performance of our system and services. By isolating work, controlling memory, and other tuning, you can achieve significant reduction in latency and increase in throughput.

My perspective comes from the microcosm of my own bare-metal (vs VM), on-premises deployment. It might not be suitable for all scenarios, especially cloud deployments, as I have little experience with HPC there. After some discussion, maybe this can be adapted as [redis.io documentation](https://redis.io/do

Awesome Java

A curated list of awesome Java frameworks, libraries and software.

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

tmux cheatsheet

As configured in my dotfiles.

start new:

tmux

start new with session name:

	package main

	import (
	"os"
	"os/signal"
	"runtime/pprof"
	"syscall"
	)

	func main() {

	# alias to edit commit messages without using rebase interactive
	# example: git reword commithash message
	reword = "!f() {\n GIT_SEQUENCE_EDITOR=\"sed -i 1s/^pick/reword/\" GIT_EDITOR=\"printf \\\"%s\\n\\\" \\\"$2\\\" >\" git rebase -i \"$1^\";\n git push -f;\n}; f"

	# aliases to change a git repo from private to public, and public to private using gh-cli
	alias gitpublic="gh repo edit --accept-visibility-change-consequences --visibility public"
	alias gitprivate="gh repo edit --accept-visibility-change-consequences --visibility private"

	# delete all your repos using gh-cli (please do not run this unless you want to delete all your repos)
	gh repo list --limit 300 --json url -q '.[].url' \| xargs -n1 gh repo delete --yes

	#!/usr/bin/python
	## gitsh (pronounced like "glitch"), an interactive wrapper for git.
	##
	## gitsh parses the output of "git status" and numbers the files for
	## you, for easy operations on multiple files.
	##
	## $ gitsh status
	## 1) M foo/bar.py
	## 2) M foo/baz.py
	## 3) A blah.sh