Posts Tagged ‘Flow’
[DevoxxGR2025] Understanding Flow in Software Development
James Lewis, a ThoughtWorks consultant, delivered a 41-minute talk at Devoxx Greece 2025, exploring how work flows through software development, drawing on information theory and complexity science.
The Nature of Work as Information
Lewis framed software development as transforming “stuff” into more valuable outputs, akin to enterprise workflows before computers. Work, invisible as information, flows through value streams—from ideas to production code. However, invisibility causes issues like unnoticed backlogs or undeployed code, acting as costly inventory. Lewis cited Don Reinertsen’s Principles of Product Development Flow, emphasizing that untested or undeployed code represents lost revenue, unlike visible factory inventory, which signals inefficiencies immediately.
Visualizing Value Streams
Using a value stream map, Lewis illustrated a typical development cycle: three days for coding, ten days waiting for testing, and 30 days for deployment, totaling 47 days of lead time, with 42 days as idle inventory. Wait times stem from coordination (teams waiting on others), scheduling (e.g., architecture reviews), and queues (backlogs). Shared test environments exacerbate delays, costing more than provisioning new ones. Lewis advocated mapping workflows to expose economic losses, making a case for faster delivery to stakeholders.
Reducing Batch Sizes for Flow
Lewis emphasized reducing batch sizes to improve flow, a principle rooted in queuing theory. Smaller batches, like deploying twice as often, halve wait times, enabling faster revenue generation. Using agent-based models, he simulated agile (single-piece flow) versus waterfall (100% batch) teams, showing agile teams deliver value faster. Limiting work-in-progress and controlling queue sizes prevent congestion collapse, ensuring smoother, more predictable workflows.