The Pragmatic Engineer
01:16:47 · Gergely Orosz
[01:16:47] S0: It was nice to get an insider look of what scaling up looks like insider products we all know and use like Slack, GitHub and Cursor. Until now, I'll admit, I never thought much about custom emojis causing a kind of scale problem. But most example of the CEO sending out a everyone gets a Friday off message to 100,000 users was a good visualization. Hundreds of people add a custom emoji and this causes An event storm of custom emoji binary sent all across the network and messages. Slack decided to fix the problem with a very simple solution, limit each message to 23 custom emoji reactions. I'm sure they could have done a more proper fix, but who will notice the 24th custom emoji not appearing anyway? It was also fascinating to hear GitHub's limit of 16 shards and why they couldn't add more. It was because of scatter queries, queries with no primary key that had to run on each and every shard before they could return. More shards would have slowed these queries down even more. The solution, of course, is to not have any queries without primary keys. But when you work with the legacy system with hundreds or thousands of queries without primary keys, rewriting those queries takes a non-trivial amount of time, not to mention that even as you're rewriting, you might have new queries added with no primary keys. Finally, it was interesting to hear how, while Maude is clearly AI-pilled, I mean, having worked on GitHub and Cursor, she still verifies pretty much everything by hand. Because when doing platform work, she says that you want to have a stable foundation. She also found that LLMs tend to write tests that just confirm the code written. Maude is now a fan of using mutation tests to have them cover edge cases. Do check out the show notes below for related to Pragmatic Engineer deep dives on cursor, GitHub, reliability, engineering, and performance topics. If you've enjoyed this podcast, please do subscribe on your favorite podcast platform and on YouTube. A special thank you if you also leave a rating on the show. Thanks, and see you in the next one.