Escaping the Oubliette (Part 3) – Bug Blitz

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Every product team I’ve ever worked in had a bug blitz at some point and often one every year or two.

There’s no arguing that a decent bug blitz is a powerful way of getting the numbers down and clearing all the bugs in a good, solid drive feels good but the necessity for them is caused by a buildup from somewhere.

If you find you’re needing a bug blitz on every release, take a look at your defect and debt prevention activities and make sure you’ve got some topping & tailing practices going on.

Usually bug blitzes are performed at the end of a project but if you’ve not done so before, try having a 4-8 week blitz at the beginning instead. You’ll run quicker afterward and (if you keep things under control), you won’t have to worry about having time to mop up at the end.

Once you’ve got the numbers down, set your maximum defect threshold (or ratchet) at this level for the remainder of the project and keep this new lower level sustained throughout development.

What’s good about a bug blitz?

A blitz is particularly useful if you can focus on areas of the product you’ll be working with soon. It’ll get your team working together (particularly if they’re newly formed) and familiar with these areas before all the major work starts.

Couple this up with developing some decent automated tests in those areas as part of the defect fixing and you’ll be developing a much safer scaffold for your new work and reduce regression risks during your next release.

You could take things further and perform some refactoring but I suggest keeping different types of activities separate at this point and just stick to straight bugs. If you have a specific functional area needing a real overhaul, it doesn’t fit the bug blitz mold. I’ll cover this aspect  in more depth when I talk about “sponsorship” for debt reduction.

I use bug blitz approaches when training up new staff. I review the defect backlog for a particularly grubby functional area and have a pair of staff take custody of it as caretakers. We pipeline the defects so that they can start with some simple introductory ones (usually low severity, noise or cosmetic stuff) and once we get confident in these we expand out into adjacent areas – it usually takes a month or two for them to really get warmed up.

The bug blitz is also a great opportunity to start new release development with a clean slate. It means no mixing types of work during feature development and gives you an opportunity to scrub the grime out and get a few new scaffolding tests in place.

What about the down-side?

First; they cost time and money. If you dedicate a team (or most of a team) to a blitz you’re not delivering anything new. This is obvious but important. What’s the impact of a month’s delay to your next release? (assuming you can ship with those bugs in there). And what will that delay do to your stakeholder relationships?

Be mindful of the impact a bug blitz can have on your customers. A high level of churn on existing functionality can be really dangerous. You might need to make a point of jumping through a few hoops to retain backwards compatibility.

Don’t be too hasty to refactor if customers are expecting certain things. If you don’t have decent automated regression tests, you really need to ensure you write at least a couple that hit the same area before you fix any defects. (I usually expect my developers to deliver at least 2 or 3 new automated tests with each bug fix).

Worse still, I’ve seen a batch of fixes in a functional area radically change behavior “for the better” according to the developers that raised the original internal defects who then discovered that customers were actually depending on existing behavior or had developed their business processes around the issues.

Sometimes, even if you think it’s ugly, it might be that way for a good reason.

With enterprise software, you’re often looking at heavily customized implementations, some of which have taken years and millions of dollars to evolve.  Smacking these with a mountain of churn on existing functionality can be painful and expensive for your customers. Whilst it makes your numbers look good, consider whether some things should really be touched.

In summary. Bug blitzes are a great way of starting with a cleaner work area and ramping up teams but beware of backwards compatibility, customer impact, time and cost pitfalls.

Read part 4 – “the litter patrol

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