Little’s law

I’m currently involved in a large redevelopment project in my day job, a question has come up. How long will a message spend in our messaging layer (but it could be applied to the system as a whole)? This is an excellent question. We can determine this using Little’s law, (Thanks Eamonn).

Little’s law states that

The long-term average number of customers in a stable system L (known as the Offered load), is equal to the long-term average arrival rate, λ, multiplied by the long-term average time a customer spends in the system, W, or: L = λW

If we know that at our peak we will be recieving 200 messages a second and the backlog in the messaging layer is 20. Then we know that at peak a message will spend 100 milliseconds in the messaging layer. The trick here is to find the correct average figures.

MBA’s

I’ve always wondered if MBA’s are worth the money spent on them. I’m thinking about doing a part time masters this year so I picked up the “The 80 Minute MBA” to see what they are all about. It’s a short read, the name gives it away but it is full of really useful information and has a great bibliography which I will use to further my own study but after reading the book I don’t think I will be starting an MBA in the autumn.

One great piece of advice on leadership from the book is

if you want someone to do a good job then give them a good job to do