Change so exciting it sets my pulse racing

Inspired by a recent blog post from Etsy, I set out to understand the human side of Continuous Delivery.  Here’s my findings:


Organisations are finally realising the significant benefits of Continuous Delivery (CD).  At the heart of CD is the utilisation of small batch sizes (this usually means frequent code releases in software development) as a means to reduce risk.  To those not practising CD this may seem somewhat counterintuitive.  I often think back ten years to a manager on a large public healthcare project who critically claimed, “you should be ashamed of the large number of software releases“.  We’d done three that month.

Frequent code releases obeys the nonsensical but true rule that: “if it hurts, do it more often“.  Martin Fowler’s simply describes this concept, listing three main reasons that this rule holds true:

  1. Most tasks become more difficult as the amount to do increases
  2. Doing anything more often increases the feedback frequency
  3. Practising something frequently leads to mastery

I feel he missed out on an important fourth reason:

The anticipation of perceived danger triggers high stress levels.  Repetition and familiarity reduce the anticipation and subsequently the stress levels.

There has been much discussion within the Operations community around the impact of stress.  At best it is a hinderance to optimum performance, at worst it has the potential to lead to burnout.

To understand if the principles of short batch sizes, cited by CD, could help reduce stress I decided to compare two types of changes – a high batch size, manual change and a low batch size, push button deployment and the accompanying stress levels.

Measuring stress

There are number of methods to measuring stress.  As stress increases the body releases the hormones adrenaline and cortisol in preparation for the “fight or flight response”. An increased heart rate is one of the easily monitored side effects.  There are a number of heart rate monitors and data loggers available on the market currently – I chose a Garmin Forerunner 410

Garmin Forerunner 410Accompanying heart rate strap


The high batch size, manual change


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