Comment by mattiemass | Hacker News Reader

Comment by mattiemass | Hacker News Reader

Author here. I'm not entirely sure why this project would be of interest, but I noticed it here so figured I'd provide a little more context.

The test suite is small, and there are no concrete results. This is because the very first truly stressful test I got to produced terrible results. Instead of continuing, I began investigating that more closely. I also opened up a developer support ticket (distinct from a Feedback) with Apple. Apple got back to me about 3 day later, pointing out a bug in my use of TextKit 2. I'm a long-time TextKit 1 user, and this stuff is new to me. I also write a lot of bugs.

TextKit 1 is a very fast system. But with this problem addressed, TextKit 2 now outperforms it by quite a bit. From a performance perspective, it seems really good so far.

If you have any other questions, let me know!

Hi!

Can you please give a high-level overview of how the benchmarks work? What are they testing? Scrolling speed? Loading time? Layout change?

These tests are being extracted from an editor project I work on. The tests themselves use the OSSignpost API for high-precision measurements combined with the XCText infrastructure for driving the UI and capturing the measurements. I've been using this combination for performance testing for a while now. It can be flakey a bit, but that's kind of the nature of UI testing sometimes. Still really great when it works.

The only truly interesting test is one that creates a 1 million line document, measures the loading time (extremely fast) and then measures the time it takes to navigate to the final line in the document. This exercises the layout system. It's really fast. On my machine TextKit 1 can do it in about 70 ms, and TextKit 2 in around 10. This isn't quite good enough for 120 fps UI on macOS machines that support it, but it's really close.

Live scrolling and window resize are both things I'm really interested in testing. But, the UI automation framework doesn't, as far as I know, have good ways of driving those interactions. But I may be able to cook something up. Ideas welcome!

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