Stable System, WIP limit and Pull System

14 Aug 2013 | Agile Culture


On myprevious blog post, I wrote that WIP limit and Pull system are the guiding rules that make a system stable.

 

 
I decided to make a visual representation for Stable System, and explore the what-if conditions for WIP limit and Pull System. 

 

 

Please note that only WIP limit or only Pull System do not guarantee system stability. The combination of both ensures the rate of work items entering the system is the rate of items exiting the system.

 

What if the WIP is not limited?

 

Not limiting WIP allows new work items to enter the system, despite of work items leaving the system. In my bar example, new bottles would be added to the bar. This makes the rate at which work item enters the system different than the rate they exit. The system is not stable.

 

What if Pull System is not being applied?

 

Not applying Pull System means that a work item exiting the system is not triggering a new one to start. In my bar example, an empty whiskey bottle is removed from it, and a new bottle is not added. This makes the rate at which work item enters the system different than the rate they exit. The system is not stable.

Paulo Caroli

Paulo Caroli is the author of the best-selling book “Lean Inception: How to Align People and Build the Right Product” (the first on a series of books about Lean Strategy and Delivery). He's also the creator of FunRetrospectives.com , a site and book about retrospectives, futurospectives and team building activities. Caroli writes on this blog frequently. Receive the next post in your email. Sign up here .

Pin It on Pinterest

X
X
X