/Debugging

How To Debug

- Phil Booth tl;dr: These steps are not specific to a particular language or paradigm, Phil's explains each of the following debugging steps: (1) Reproduce the bug. (2) Reproduce it again. (3) Don't reproduce it. (4) Understand the code. (5) Observe state. (6) Write down what you (think you) know. (7) Rule things out. (8) Walk the dog. (9) Rewrite a component. (10) Write a failing test case. (11) Fix it.

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The Heisenbug Server

- Oren Eini tl;dr: "A user reported that they observed nodes in the cluster “going dark”. Basically, they would stop communicating with the rest of the cluster, but would otherwise appear functional. Both the internal and external metrics were all fine, the server would just stop responding to anything over the network. The solution for the problem was to restart the service, but the problem would happen every few days."

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A Beginner’s Guide To Chrome Tracing

- Nolan Lawson tl;dr: Chrome tracing lets you record a performance trace that captures low-level details of what the browser is doing. It’s mostly used by Chromium engineers themselves, but it can also be helpful for web developers when a DevTools trace is not enough. This post is a short guide on how to use this tool, from a web developer’s point of view. I’m not going to cover everything – just the bare minimum to get up and running."

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A Debugging Manifesto

- Julia Evans tl;dr: Julia discusses the attitude and approach to take when debugging, explaining the following: (1) Inspect, don’t squash. (2) Being stuck is temporary. (3) Trust nobody and nothing. (4) It’s probably your code. (5) Don’t go it alone. (6) There’s always a reason. (7) Build your toolkit. (8) It can be an adventure.

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Tips For Analyzing Logs

- Julia Evans tl;dr: 14 useful tips including the following: (1) Search for the request’s ID - often log lines will include a request ID and searching for the request ID of a failed request will show all the log lines for that request. (2) Build a timeline - keeping all of the information straight in your head can get confusing, so keeping a debugging document where I copy and paste bits of information.

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Twenty Five Thousand Dollars Of Funny Money

tl;dr: "I had been at the company something like six weeks and had changed a line of source code to fix a bug (logging), to uncover another bug (wrong argument count), to enable yet another bug (wrong units, and zero type safety) that gave 25 grand worth of funny money to anyone who clicked! And I had clicked! And I got a friend to click! And other people got it too!"

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Debugging Mysterious Traffic From Boardman, OR

tl;dr: "A quick Google search revealed that Boardman, OR hosts a large AWS data center. Turns out that because Boardman has access to electricity from hydropower, it is cheaper than other data centers and is therefore preferred by many."

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Some Ways To Get Better At Debugging

- Julia Evans tl;dr: Julia read some papers on debugging and found the following categorization very helpful, elaborating on each of the following categories: (1) Learn the codebase. (2) Learn the system. (3) Learn your tools. (4) Learn strategies. (5) Get experience.

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Modern Web Debugging In Chrome DevTools

- Bramus Van Damme Victor Porof tl;dr: "As an author, you want to see and debug the code that you wrote, not the deployed code. To make up for it, you can now have the tree show the authored code instead. This makes the tree more closely resemble source files you get to see in your IDE, and these files are now separated from the deployed code." The authors discuss how this works and other additions to Chrome's DevTools. 

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Weird Monitor Bugs People Sent Me In The Last 5 Years

- Alin Panaitiu tl;dr: "I get tons of email about Lunar, a macOS app for getting intelligent adaptive brightness on external monitors. A lot of these complain about bugs, but sometimes, after a good multi day chase, I conclude it’s actually a monitor bug. I try to help and provide a workaround whenever I can. But anyway, here’s a small collection of those bugs."

featured in #347