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Showing posts from June, 2020

Podcast: The Post Office Horizon Scandal

In this episode, we look at the Post Office Horizon scandal, an app that caused what some people are describing as the largest miscarriage of justice in British legal history.
We look at some bugs, the legal judgements and what might have gone wrong at the Post Office to allow things to go so off track. I analyse what we can learn from the disaster to help stop this from happening in our own projects.

The show notes and transcripts are available for free.

Podcast: Voting Machine Fail

We wind the clock back to November 2019 and investigate the failure of voting machines in Northampton County, Pa., USA. We break down what went wrong, what caused the problem and what we can learn about the risks of software development from this high profile incident.

The show notes and transcripts are available for free.

Avoiding Wild Goose Chases While Debugging.

When I’m debugging a complex system, I’m constantly looking for patterns. I just ran this test code... What did I see in the log? I just processed a metric $^&*-load of data, did our memory footprint blip?
I’m probably using every freedom-unit of screen space to tail logs, run a memory usage tool, run an IDE & debugger, watch a trace of API calls, run test code… And I’m doing this over and over. Then I see it. Bingo, that spike in API calls hits only when that process over there jumps to 20% processor usage when the app also throws that error.
Unfortunately, I may have been mistaken. On a sufficiently complex system, the emergent behaviour can approach the appearance of randomness. Combinatorial explosions are for real, and they are happening constantly in your shiny new MacBook.


My bug isn’t what I think it is. I’m examining so many variables in a system with dozens of subsystems at play, it's inevitable I will see a correlation. We know this more formally as the multipl…