This is a post in my series on things I've remarked on in code review.

Say there's a commit with a message like

Bump number of workers to fix image upload problem

and a change like

- "number_of_workers": 4,
+ "number_of_workers": 8,

Then I'm left wondering why it wasn't at 8 to start with. Or why we don't bump it all the way to 16, or 32. Surely more workers are better?

Usually there's a trade-off at play. More workers use more memory, perhaps.

If you tweak a value I want to know that you've considered that trade-off.

Ideally, a code comment (rather than the commit message) will explain what the trade-off is. Then the next tweaker sees it, and the next code reviewer too.