Two Things Everyone Should Know About Queues

If you are in the performance business, you should know a lot about queues. How to use them to find performance problems, predict issues, plan your capacity, model your load test results, etc. Queues are just a part of what you should know and be comfortable discussing.

But what if you are not a performance professional? What if you are a sales person or a manager or a dentist? Do you still need to understand queues?

Obviously not everyone should know queues at a precise mathematical level. But queues are everywhere, and sometimes I wish people around me understood queues better. It’ll make it easier for me to explain things. There are two things I think everyone should know about queues:

  1. If it takes me one hour on average to handle a request, and I get one request every hour – most of the time requests will be delayed due to queueing and backlog. Running your DBAs (or servers, or doctors, or toll-booths) at full utilization with every minute accounted for means queueing and delays.
  2. If there are multiple servers (or DBAs or DMV clerks), the most efficient way to get service is to arrange all the requests in a single queue and have all servers accept requests from that queue. The way supermarkets do it – a different queue per cashier is inefficient. Deciding that you want all your requests to be handled by a specific DBA because she is better looking is also less efficient than entering the request in the general DBA queue.

Spread the word 🙂

4 Comments on “Two Things Everyone Should Know About Queues”

  1. In our DBA team, requests are allocated to the DBA who does the worst job of avoiding eye contact with the developer as he/she tentativily approaches our group of desks.

  2. I thought that choosing the supermarket queue according to the looks of the cashier was a time-honoured technique. You’re saying now that it’s inefficient?

    In my experience, when it comes to DBA’s the point is moot. No offence to any I’ve worked with …

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