97 Things Every Java Programmer Should Know

Chapter 26. Frequent Releases Reduce Risk

Chris O’Dell

“Frequent releases reduce risk”—this is something you hear all the time in conversations about continuous delivery. How exactly is this the case? It sounds counterintuitive. Surely, releasing more often is introducing more volatility into production? Isn’t it less risky to hold off releasing as long as possible, taking your time with testing to guarantee confidence in the package? Let’s think about what we mean by risk.

What Is Risk?

Risk is a factor of the likelihood of a failure happening combined with the worst-case impact of that failure:

• Risk = Likelihood of failure × Worst-case impact of failure

Therefore, an extremely low-risk activity is when failure is incredibly unlikely to happen and the impact of the failure is negligible. Low-risk activities also include those where either of these factors—likelihood or impact—is so low that it severely reduces the effect of the other.

Playing the lottery is low-risk: the chance of failing (i.e., not winning) is very high, but the impact of failing (i.e., losing the cost of the ticket) is minimal, so playing the lottery has few adverse consequences.

Flying is also low-risk due to the factors being balanced the opposite way. The chance of a failure is extremely low—flying has a very good safety record—but the impact of a failure is extremely high. We fly often, as we consider ...