Monday, January 17, 2011

Lean Development : Eliminate Waste

This post has taken longer than I'd hoped, and is consequently less polished than I'd hoped... but here goes...

The first entry in our list of Lean Development concepts shows leans focus on efficiency:
Eliminate Waste - No Extra Features, Churn or Boundaries
Before we can eliminate waste we must first understand what waste is. I think of this concept as "Don't do what you don't need to do" and waste is any resource use that is not driving your core business.

Here is a list of 7 deadly wastes - which I believe come from the original Toyota lean methodology.

  1. Transportation
  2. Inventory
  3. Motion
  4. Waiting
  5. Over-Processing
  6. Over-Production
  7. Defects and Rework
In most of these cases the resource that is being wasted is time. 
I'm going to cover the first 3 today, and more tomorrow.

Transporting a commodity from A to B takes time and may have a monetary cost. But in a digital world this is less applicable. However if you think of this as meaning inefficiencies in your supply chain this may make more sense. How long does it take you to get a "ready" version of the code out to your customers? How painful is this process? How robust?  What are you doing in the process that can be automated or removed? Any manual interaction that is not needed is wasted effort. Any unneeded delays are wasted time. 

Inventory in a software sense is completed features not shipped to the users. A feature is not providing value to a customer when it is sitting in your development version of the software. The sooner you can get a completed (and tested!) feature out to you users, the sooner it provides value to them, and thus dirves value for you. Of course if every push to the users is taking a couple of days of effort then you have a transport issue that needs fixing first.

Motion, to me means one developer (or task) doing unnecessary actions as part of its progress through the conceptual pipe from idea to implementation. These often crop up as bureaucracy - paper work that will be discarded, double entry into multiple bug tracking systems, emails to supervisors, stuff that makes a developer busy but not productive. This is wasted effort and time.

Waiting.. this usually means waiting for feedback from another party, or waiting for compilation, or waiting for  tests to run. The developer ends up doing nothing productive, or is less-productive due to context switching between tasks. So parallelize or speed up the process. Tests should be near instantaneous - your full test suite takes an hour to run - split it up across 10 machines and it should take 6 minutes. Compilation should be fast (and incremental) - use ccache, distcc or something like that. Feedback should be fast or at least predictable.

Well thats it for today, as I said its a bit choppy butt hopefully you got something out of it.

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