This document discusses concepts from queueing theory and how they relate to software development processes. It explains Little's Law, which relates work in progress, throughput, and cycle time. Having lower work in progress can lead to shorter cycle times and faster feedback. The document also discusses bottlenecks, noting that throughput can never exceed the bottleneck. Managing bottlenecks, work in progress, and ensuring capacity is balanced can help optimize and stabilize development processes.

1. Queueingtheoryinsoftware development Håkan Forss - hakan.forss@avegagroup.se - @hakanforss

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3. What can traffic inteach you about yourdevelopment process Håkan Forss - hakan.forss@avegagroup.se - @hakanforss

9. Little’s Law Work-in-Process Throughput Cycle Time =

10. Little’s Law 12 12 / min 1 min =

11. Little’s Law 6 12 / min 0,5 min=

12. Little’s Law 24 12 / min 2 min =

13. 8 cars / min 4 cars / min With less work-in-progress Shorter cycle time Faster feedback Makes problems visible faster

15. TheoryofConstraints

18. 5

19. Don’t allow inertia to cause a system constraint.

20. Capacity = 4 Capacity = 6 Capacity = 6 Throughput = 4 Bottlenecks You can never go faster than your bottleneck

21. Bottlenecks Throughput = 2 You can never go faster than your bottleneck Do whatever you can to make your bottleneck 100% utilized Try your hardest to avoid problems at you bottleneck You can’t make up for lost capacity at you bottleneck

22. Throughput = 4 You can never go faster than your bottleneck As long as capacity in front of the bottleneck is equal to or grater than the bottleneck you will go as fast as your bottleneck Full use of a higher capacity in front of the bottleneck will make cycle time go up Bottlenecks

23. Bottlenecks Throughput = 4 You can never go faster than your bottleneck As long as capacity is equal to or grater after the bottleneck you will go as fast as your bottleneck Higher capacity after the bottleneck than at the bottleneck will not improve throughput

32. Non-instantavailabilityresource A resource that is not available all the time

33. Non-instantavailabilityresource & bottleneck

38. You can never go faster than your bottleneck Balance demand against throughput to keep work-in-progress low Low work-in-progress Keeps cycle time down Makes bottlenecks visible faster

40. Slow down to go faster Slowing down can stabilize the process flow A stable process can go faster

43. Håkan Forss Mail: hakan.forss@avegagroup.se Twitter: @hakanforss Blog: http://hakanforss.wordpress.com/