Move Fast Without Breaking Anything

A cautionary tale

I received the first critical feedback of my career after my first promotion. Even though I was having more impact on my projects, my manager told me that I needed to change something or else we would have a serious problem.

Career growth for junior engineers comes from completing larger features. But, writing more code makes it easier to break things. Here’s two ways to move fast without breaking anything.

I got my first promotion through sheer volume of work. I shipped larger features by averaging ~5 code changes a day. I could’ve gotten promoted with less output if I had discussed expectations for the next level with my manager (which I will address in a future post). But that wasn’t the main thing slowing my growth.

Ryan Peterman @ryanlpeterman

1/4 When I was a new grad, I brought nothing to my 1:1s with my manager. I got promoted on the sheer volume of work I was doing eventually, but it felt more like luck than anything.

The main issue was that I sometimes broke things because I was making so many changes. I addressed my manager’s warning by coming up with ways to move fast without breaking anything. There are two main tactics which worked well for me:

1. Batching test plans - I spent a lot of time testing every code change I made. To make testing faster, I created large stacks of commits that were all loosely related on the same code path. I then ran tests covering the entire stack all at once. For a stack of 10 commits, I only paid the cost of testing once while making sure nothing broke.

2. Gating all changes - I used feature flags on every code change I made so that users couldn’t access code paths while I worked on them. That way I could land code as fast as I wanted without worrying about breaking anything. Then when I was ready to release the code, I would verify everything all at once by turning on the flag for a small population while monitoring it.

Look for ways to optimize your workflow to become more productive. In this case, I saved a ton of time on testing by batching and gating features. Code review is another major bottleneck that can slow you down as I discussed in this Twitter thread:

Ryan Peterman @ryanlpeterman

If you decompose your code into small, encapsulated changes, the bottleneck for landing it faster comes from getting it reviewed. There are two effective levers to get code reviewed faster.

Now it’s your turn: aside from testing and code review, are there any other major bottlenecks in your workflow that slow you down?

Thanks for reading,
Ryan Peterman