Category: posts
Using less memory to look up IP addresses in Mess With DNS Some notes on upgrading Hugo Terminal colours are tricky Some Go web dev notes Reasons I still love the fish shell Migrating Mess With DNS to use PowerDNS Go structs are copied on assignment (and other things about Go I'd missed) Entering text in the terminal is complicated Reasons to use your shell's job control New zine: How Git Works! Notes on git's error messages Making crochet cacti Some Git poll results The "current branch" in git How HEAD works in git Popular git config options Dealing with diverged git branches Inside .git Do we think of git commits as diffs, snapshots, and/or histories? Some notes on NixOS 2023: Year in review Mounting git commits as folders with NFS git branches: intuition & reality Some notes on nix flakes How git cherry-pick and revert use 3-way merge git rebase: what can go wrong? Confusing git terminology Some miscellaneous git facts New talk: Making Hard Things Easy In a git repository, where do your files live? Notes on using a single-person Mastodon server What helps people get comfortable on the command line? Some tactics for writing in public Behind "Hello World" on Linux Why is DNS still hard to learn? Lima: a nice way to run Linux VMs on Mac Open sourcing the nginx playground New zine: How Integers and Floats Work Some blogging myths New playground: memory spy Introducing "Implement DNS in a Weekend" New talk: Learning DNS in 10 years New playground: integer.exposed A list of programming playgrounds Building a custom site for zine feedback Some possible reasons for 8-bit bytes How do Nix builds work? Some notes on using nix Writing Javascript without a build system Print copies of The Pocket Guide to Debugging have arrived Why does 0.1 + 0.2 = 0.30000000000000004? Examples of problems with integers Examples of floating point problems Some business graphs for 2022 New zine: The Pocket Guide to Debugging A debugging manifesto Tips for analyzing logs A couple of Rust error messages Making a DNS query in Ruby from scratch Why do domain names sometimes end with a dot? How to send raw network packets in Python with tun/tap Some ways to get better at debugging A toy remote login server What happens when you press a key in your terminal? Monitoring tiny web services Notes on running containers with bubblewrap sqlite-utils: a nice way to import data into SQLite for analysis Pages that didn't make it into "How DNS Works" New zine: How DNS Works! A list of new(ish) command line tools Implementing a toy version of TLS 1.3 Celebrate tiny learning milestones How to use undocumented web APIs Some tiny personal programs I've written Some things about getaddrinfo that surprised me Things that used to be hard and are now easy The multiple meanings of "nameserver" and "DNS resolver" A toy DNS resolver Reasons for servers to support IPv6 Hosting my static sites with nginx Some ways DNS can break How to find a domain's authoritative nameservers Why might you run your own DNS server? 2021: Year in review New tool: Mess with DNS! DNS "propagation" is actually caches expiring How to use dig Debugging a weird 'file not found' error Some notes on using esbuild How do you tell if a problem is caused by DNS? How to get useful answers to your questions Tools to explore BGP All my zines are now available in print! New tool: an nginx playground Teaching by filling in knowledge gaps Debugging by starting a REPL at a breakpoint is fun Quadratic algorithms are slow (and hashmaps are fast) Patterns in confusing explanations Write good examples by starting with real code Reasons why bugs might feel "impossible" You can now buy print version of my zines! Blog about what you've struggled with How to look at the stack with gdb The OSI model doesn't map well to TCP/IP I put all of my comics online! Notes on building debugging puzzles What problems do people solve with strace? A tool to spy on your DNS queries: dnspeep Get better at programming by learning how things work Things your manager might not know A little tool to make DNS queries Day 57: Trying to set up GitHub Actions Day 56: A little WebAssembly Day 53: a little nginx, IPv6, and wireguard Day 52: testing how many Firecracker VMs I can run Day 51: Fixed my logging and made a couple of puzzles Day 50: Building some tarballs for puzzles, and trying to make a kernel boot faster Day 49: making the VMs boot faster Day 48: Another Go program, and a little vim configuration Day 47: Using device mapper to manage Firecracker images Day 46: debugging an iptables problem Firecracker: start a VM in less than a second Day 44: Building my VMs with Docker Day 43: Building VM images Day 42: Writing a Go program to manage Firecracker VMs Day 41: Trying to understand what a bridge is Day 40: screen flickering & a talk about containers Day 39: Customizing gotty's terminal Day 38: Modifying gotty to serve many different terminal applications at once Day 37: A new laptop and a little Vue Server-sent events: a simple way to stream events from a server Day 35: Launching my VMs more reliably Daily blog posts about my time at RC Day 34: Learning about qemu Day 33: pairing is magic and beautiful git diffs Day 32: A Rails model that doesn't use the database with ActiveHash Docker Compose: a nice way to set up a dev environment 2020: Year in review Day 24: a short talk about blogging myths, and a debugging tip Day 23: a little Rails testing Day 22: getting OAuth to work in Rails Day 21: wrangling systemd & setting up git deploys to a VM Day 19: Clustering faces (poorly) using an autoencoder How I write useful programming comics Day 20: trying to figure out how Google Cloud IAM works Day 18: an answer to an autoencoder question Day 17: trying to wrap my head around autoencoders An attempt at implementing char-rnn with PyTorch Day 13: BPTT, and debugging why a model isn't training is hard Day 11: learning about learning rates New zine: Hell Yes! CSS! Day 10: Training an RNN to count to three Day 9: Generating a lot of nonsense with an RNN Day 8: Start with something that works Day 5: drawing lots of faces with sketch-rnn How do you write simple explanations without sounding condescending? Day 3: an infinitely tall fridge Day 2: Rails associations & dragging divs around Day 1: a confusing Rails error message A new way I'm getting feedback on my zines: beta readers! I'm doing another Recurse Center batch! A few things I've learned about email marketing ninja: a simple way to do builds Wizard Zines' first print run: Help! I have a Manager! Implementing 'focus and reply' for Fastmail with JMAP Some possible future zines Some more CSS comics An attempt to make a font look more handwritten Some CSS comics When your coworker does great work, tell their manager scanimage: scan from the command line! Twitter summary from 2020 so far saturday comics: a weekly mailing list of programming comics Tell candidates what to expect from your job interviews entr: rerun your build when files change A little bit of plain Javascript can do a lot What happens when you update your DNS? Questions to help people decide what to learn Metaphors in man pages Why strace doesn't work in Docker New zine: How Containers Work! When debugging, your attitude matters Getting started with shaders: signed distance functions! Questions you can ask about compensation New zine: Become a SELECT Star! PaperWM: tiled window management for GNOME 2019: Year in review "server" is hard to define How tracking pixels work Challenge: find Twitter memes with suffix arrays Solutions to the tiny window manager challenge Challenge: Write a bouncy window manager What makes a programming exercise good? How containers work: overlayfs Some notes on vector drawing apps Some research on shipping print zines SQLite is really easy to compile Your Linux Toolbox: a box set of my free zines SQL queries don't start with SELECT Zine revenue for 2019 Notes on building SQL exercises Taking a year to explain computer things New zine: HTTP: Learn your browser's language! How to put an HTML page on the internet How to write zines with simple tools git exercises: navigate a repository curl exercises Get your work recognized: write a brag document What does debugging a program look like? Why are monoidal categories interesting? New zine: Bite Size Networking! Organizing this blog into categories !!Con 2019: submit a talk! Networking tool comics! A few early marketing thoughts Some nonparametric statistics math 2018: Year in review New talk: High Reliability Infrastructure Migrations How do you document a tech project with comics? An example of how C++ destructors are useful in Envoy Some notes on running new software in production Tailwind: style your site without writing any CSS! When does teaching with comics work well? New zine: Oh shit, git! Some Envoy basics What's a senior engineer's job? Some possible career goals Why sell zines? New zine: Help! I have a manager! Build impossible programs An awesome new Python profiler: py-spy! Editing my blog's HTTP headers with Cloudflare workers Who pays to educate developers? How to teach yourself hard things I started a corporation! A few recent podcasts New zine: Bite Size Command Line! IP addresses & routing netdev day 2: moving away from "as fast as possible" in networking code netdev day 1: IPsec! How I use Wireshark Batch editing files with ed How to get a core dump for a segfault on Linux New zine: Profiling & tracing with perf!! Talk: Building a Ruby profiler Reverse engineering the Notability file format Open source sabbatical = awesome Documentation site for rbspy! Talks I'd love to see at RustConf A few things I've learned about computer networking How does the internet work? podcast Prototyping an ltrace clone using eBPF Measuring a blog's success: focus on conversations, not page views Profiler week 6/7: more experiments, and a `report` subcommand! Working remotely, 4 years in Writing performance reviews with positive constructive feedback Profiler week 5: Mac support, experiments profiling memory allocations Writing eBPF tracing tools in Rust Spying on a Ruby process's memory allocations with eBPF Profiler week 4: callgrind support, containers, Mac progress! I think I found a Mac kernel bug? How do you spy on a program running in a container? How do you read the memory maps of a Mac process? Profiler week 3: refactoring, better testing, and an alpha release! Profiler week 2: support for 1.9.3 -> 2.5.0, and line numbers! Should I pause a Ruby process to collect its stack? Rust in 2018: it's way easier to use! Profiler adventures: resolving symbol addresses is hard! Profiler week 1: testing & profiling stripped binaries How does gdb call functions? 2017: Year in review How I set up an automatic weekly blog digest A perf cheat sheet My first Rust macro Debugging a segfault in my Rust program Bindgen: awesome Rust tool for generating C bindings How are Ruby's headers different from Python's headers? How often do Ruby's stack struct definitions change? How do Ruby & Python profilers work? Taking a sabbatical to work on Ruby profiling tools New zine: So you want to be a wizard What's a reference in Rust? Linux comics: a small zine How do groups work on Linux? Glitch: write fun small web projects instantly Binder: an awesome tool for hosting Jupyter notebooks Operating a Kubernetes network Reasons Kubernetes is cool How to teach technical concepts with cartoons Profiling Go programs with pprof How to answer questions in a helpful way How I spent my time at the Recurse Center Cool vim feature: sessions! Data structure: the treap! Finding out if/why a server is dropping packets Debugging netlink requests What's a network interface? Telling people what you're working on Learning at work Figuring out how to contribute to open source How Kubernetes certificate authorities work Cherry picking commits & shell scripting in golang How does the Kubernetes scheduler work? Linux tracing zine Linux tracing systems & how they fit together Notes on BPF & eBPF 3 short screencasts (/proc, tcpdump, strace) a tiny whack-a-mole game What can developers learn from being on call? Awesome NLP tutorials by Allison Parrish Log-structured storage Iptables basics A few things I've learned about Kubernetes Async IO on Linux: select, poll, and epoll Handwritten books "Let's learn tcpdump" zine: now available for everyone A small website mystery Like zines about computers? You might love Bubblesort Zines Using the Strict-Transport-Security header New zine: let's learn tcpdump! No feigning surprise The fish shell is awesome Some good "Statistics for programmers" resources Making small culture changes netdev conference, day 3 netdev conference, day 2 How to filter packets super fast: XDP & eBPF! netdev conference, day 1 Slow down your internet with tc Bash scripting quirks & safety tips Blogging principles I use ftrace: trace your kernel functions! Writing down my career So you want to be a wizard Swapping, memory limits, and cgroups Hiring & opportunity How do these "neural network style transfer" tools work? Weird unix thing: 'cd //' How big can a packet get? A magical machine learning art tool Dissecting an SSL certificate New zine: "Networking! ACK!" Choosing the "best software" A tiny zine about machine learning An idea for a programming book How do you make an awesome team? Rules of programming experiments How to ask good questions Systems We Love 2016 A container networking overview 2016: Year in review What's interesting about UDP? How much memory is my process using? More drawings about computers Things to learn about Linux "A Critique of the CAP Theorem" Ideas about how to use AWS Why cute drawings? A few drawings about Linux What happens when you run a rkt container? Service discovery at Stripe A few questions about open source Running containers without Docker A litmus test for job descriptions Consistency vs availability (wat?) What's devops? Operations for software developers for beginners What even is a container: namespaces and cgroups Switching to Hugo ★ What happens when you start a process on Linux? A list of Linux container software "I just want to run a container!" ★ Getting things done A swiss army knife of debugging tools: talk & transcript Some questions about Docker and rkt How I got a CS degree without learning what a system call is ★ Learning systems programming with Rust New zine: Linux debugging tools you'll love Asking good questions is hard (but worth it) How (and why) I made a zine Why do UDP packets get dropped? Release it, then build it ★ How do you decide what to work on? How does gdb work? A few sketches Benchmarking correctly is hard (and techniques for doing it better) How do HTTP requests get sent to the right place? ★ Linux debugging tools I love PolyConf 2016 ★ Why do we use the Linux kernel's TCP stack? Using ltrace to debug a memory leak Should you be scared of Unix signals? ★ How to spy on a Ruby program A useful new strace feature Ideas for making better conference talks & conferences Learning to like design documents Three ways to solve hard programming problems "advice" for aspiring tech bloggers Notes from my PyData Berlin keynote A few reasons to be skeptical of machine learning Investigating Erlang by reading its system calls homu + highfive: awesome bots that make open source projects easier A second try at using Rust A workshop on strace & tcpdump What are SSL ciphers & session keys? The Etsy site performance report is amazing How does knowledge get locked up in people's heads? CDNs aren't just for caching you can take the derivative of a regular expression?! Some links on Java garbage collection Java garbage collection can be really slow Looking inside machine learning black boxes Some of my favorite blogs I conquered thread pools! For today, at least. Thread pools! How do I use them? I/O matters. How do you do capacity planning? tcpdump is amazing How does perf work? (in which we read the Linux kernel source) Women-only spaces are a hack Surprises in Ruby HTTP libraries What is "the stack"? perf top: an awesome way to spy on CPU usage How to measure your CPU time: clock_gettime! Why I love log files Have high expectations for your computers ★ TIL: clock skew exists How CPU load averages work (and using them to triage webserver performance!) Fast integer sets with Roaring Bitmaps (and, making friends with your modern CPU) Sendfile (a system call for web developers to know about!) Guessing Linux kernel registers Calling C from Rust A few notes on my CUSEC talk ★ Why I ❤ Rust Talking about stock options = awesome Java isn't slow Winning the bias-variance tradeoff Surviving meetings while remote ★ Things you should know about stock options before negotiating an offer 2015: Year in review ★ How to trick a neural network into thinking a panda is a vulture Women in Machine Learning 2015 (fun!!!) Why Ruby’s Timeout is dangerous (and Thread.raise is terrifying) ★ How I got better at debugging ★ Why you should understand (a little) about TCP Docker is amazing PAPERS ARE AMAZING: Profiling threaded programs with Coz ★ A millisecond isn't fast (and how we made it 100x faster) Is machine learning safe to use? An argument for hiring junior developers Some easy statistics: Bootstrap confidence intervals AdaCamp Montreal 2015 A zine about strace Learning at open source sprints (no preparation required) A few spy tools for your operating system (other than strace!) Seeing system calls with perf instead of strace Senior engineering & fantasy heroes Nancy Drew and the Case of the Slow Program 1:1 topic ideas You can choose who submits talks to your conference How the locate command works (and let's write a faster version in one minute!) ★ How gzip uses Huffman coding ★ How I learned to program in 10 years A/A testing Why a C++ programmer might say "I could never write Python" Data Day Texas 2015 On reading the source code, not the docs Programming doesn't belong to men (it belongs to me) Fear makes you a worse programmer Reproducing awesomeness ★ Diving into concurrency: trying out mutexes and atomics Spying on Hadoop with strace LD_PRELOAD is super fun. And easy! PyData NYC (I gave a machine learning talk! yay!) Harm reduction for developers Fun with machine learning: logistic regression! Fun with machine learning: does your model actually work? What women in technology really think (150 of them, at least) Working remote, 8 months in (seeing humans is important!) How to set up a blog in 5 minutes How does SQLite work? Part 2: btrees! (or: disk seeks are slow don't do them!) ★ How does SQLite work? Part 1: pages! Strange Loop 2014 You can be a kernel hacker! How is a binary executable organized? Let's explore it! ★ What happens if you write a TCP stack in Python? Pair programming is amazing! Except... when it's not. Open sourced talks! Ruby Rogues podcast: systems programming tricks! Fun with stats: How big of a sample size do I need? How I did Hacker School: ignoring things I understand and doing the impossible !!Con talks are up Machine learning isn't Kaggle competitions Asking questions is a superpower Working remote, 3 months in Should my conference do anonymous review? Anonymous talk review is amazing. Diving into HDFS I can spy on my CPU cycles with perf! ★ Computers are *fast*! Stopping to think ★ Don't feel guilty about not contributing to open source ★ Debug your programs like they're closed source! ♥ PyCon Becoming a better developer (it's not just writing more programs) "Ask if you have questions" isn't enough Reports from remote-land: remote pairing works great! Recovering files using /proc (and spying, too!) My Rust OS will never be finished (and it's a success!) ★ Writing an OS in Rust in tiny steps (Steps 1-5) Debugging shared library problems with strace Hacker School's Secret Strategy for Being Super Productive (or: Help.) Pair programming More practical uses for strace! Using strace to avoid reading Ruby code A resume workshop idea A bookmarklet to flee from Mailman archives Spying on ssh with strace "How was Hacker School?" A few blogs I really like Three steps to learning GDB Sounding confident in interviews CUSEC = fun What my technical interviews have looked like You should give talks. They will be awesome. Here's why! ★ 4 paths to being a kernel hacker Some things my kernel can't do Sketches for a graph layout engine ★ Questions I'm asking in interviews Coding strategies ★ When is "guys" gender neutral? I did a survey! ★ A pandas cookbook Understanding how killall works using strace Day 46: Never Graduate Day 45: I now have Rust code for executing executables! Day 44: qemu + gdb = so great ★ Day 43: SOMETHING IS ERASING MY PROGRAM WHILE IT’S RUNNING (oh wait oops) Day 42: How to run a simple ELF executable, from scratch (I don't know) Day 41: Linkers are upsetting Day 39: Writing malloc wrong, for fun Day 40: 12 things I learned today about linkers. Day 40: Linkers are amazing. Day 38: After 6 days, I have problems that I can't understand at all ★ Day 37: After 5 days, my OS doesn't crash when I press a key ★ Day 36: On programming without malloc Day 35: Types in Rust, for beginners How to call Rust from assembly, and vice versa Videos from PyData NYC are up! ★ What happens when you run 'Hello, world' Writing a kernel using rustboot & rust-core Day 34b: Writing curl using my TCP stack Day 34: The tiniest operating system Day 33: How to make music with ClojureScript Day 32: Magical Orchestra!!! Day 31: Binary trees with core.logic! Day 30: Making music in Clojure with Overtone. Clojure bugs with laziness! Fun! Day 29: Trying out Emacs! Day 28: Made a git workflow visualization webapp! Day 27: Automatically testing changes in state! Visualizing my Git workflow! Floats! Day 25: ACK all the things Day 26: Trying to describe the TCP state machine in a readable way. Failing. Women in Technology workshop at PyData NYC Day 24: Unit testing this TCP library Day 22: Got some TCP packets back! Day 23: Started writing a TCP stack in Python NYC Python talk Day 21: Trying to TCP Day 19: A few reasons why networking is hard ★ Day 20: Traceroute in 15 lines of code using Scapy Day 18: ARP cache poisoning (or: In ur connection, sniffing ur packets) Day 17: How to write a buffer overflow exploit ★ Day 16: gzip + poetry = awesome Do Rails programmers use node.js? Visualizing correlations in command usage Day 15: How a .gz file is structured, redux Day 14: When it's hard to write tests, that's when I should be testing Day 13: Off by one errors Day 12: Why Julia likes Julia Day 10: Goals. Goals? Maybe I need to be *reading* more code? Day 11: How does gzip work? Day 9: Bytecode is made of bytes! CPython isn't scary! Day 8: Julia writes Julia! And remembers that open source is hard. Day 7: An echo server in Clojure Day 6: I wrote a rootkit! Day 5: I wrote a kernel module!!! Where to find bike sharing systems' data feeds Day 4: Processes vs threads, and kernel modules! Day 3: What does the Linux kernel even do? Day 2: netcat fun! Day 1: What does a shell even do? Hacker School Day 1: Messing around with the stack in C Hacker School Day -4: unit testing in C. checkmk! Julia Serano's 'Excluded' PyData Boston 2013 Open Data Exchange 2013 Transit maps: 1941 vs 2011 Graphing bike path data with IPython Notebook and pandas Trying out Octopress Montreal All-Girl Hack Night #2: now with cookies Montreal All-Girl Hack Night #1: AMAZING