4 ms·

If I remember correctly, in the mathematical model a global queue only helps with variance, but not the expected waiting time or throughput. In the real world

by zawerf 8y ago

If I remember correctly, in the mathematical model a global queue only helps with variance, but not the expected waiting time or throughput. In the real world you won't have the same service time for both cases since you need to add in walking from the global queue to the individual registers. You will end up with increased confusion from customers who always have to be on the lookout for next open spot at slightly higher waiting time and a more confusing store layout, all for just lower variance. Is it worth it?

FakeComments 8y ago
The Target by my house implemented global queuing at the registers and honestly, it’s the nicest store to shop at. Similarly, I’m not sure the global queue adds more than a step or two to routing, since you have to walk to the register either way, and it replaces a complex mental task, picking the optimal queue then monitoring if you should switch, with a simple one, waiting in a line while looking for a wave. In my experience, a global queue is less taxing than having to queue in lines would be.
- scott_s 8y ago
  Yes, agreed, this is what I meant by “basically zero-cost queue synchronization”. Global queues tend to lead to more balanced systems, but at the cost of constant global queue access. But in grocery store checkouts, that cost is basically zero.
SilasX 8y ago
Yes, but variance is a thing you want to minimize too, since it forces entrants to be less efficient in allocating their own time since they have to block off more time to cover the n-standard deviations wait-time, which means they can’t be as efficient even if they get the fast queue since they didn’t schedule anything for that time. It may or may not be worth the extra overhead.
TeMPOraL 8y ago
> In the real world you won't have the same service time for both cases since you need to add in walking from the global queue to the individual registers. In all single-queue systems I've seen, this is solved by the cashier pressing the "register free" button before being finished with the previous customers. > You will end up with increased confusion from customers who always have to be on the lookout for next open spot I find it, and I find it pretty clearly, for the opposite to be true. In single-queue system, I can literally sleep-walk and read books/browse social media the entire queue up until the point I reach the front end, where I only need to pay attention to the sign telling me to which register to go. With multiple queues, I feel the need to pay attention to whether or not another register is opening, or whether or not one of the customers in front of me has high handling time risk - so that I can switch queues early on.
entity345 8y ago
> You will end up with increased confusion from customers who always have to be on the lookout for next open spot That simply does not happen in the real world.

by zawerf 8y ago

FakeComments 8y ago

The Target by my house implemented global queuing at the registers and honestly, it’s the nicest store to shop at. Similarly, I’m not sure the global queue adds more than a step or two to routing, since you have to walk to the register either way, and it replaces a complex mental task, picking the optimal queue then monitoring if you should switch, with a simple one, waiting in a line while looking for a wave. In my experience, a global queue is less taxing than having to queue in lines would be.

scott_s 8y ago
Yes, agreed, this is what I meant by “basically zero-cost queue synchronization”. Global queues tend to lead to more balanced systems, but at the cost of constant global queue access. But in grocery store checkouts, that cost is basically zero.

SilasX 8y ago

Yes, but variance is a thing you want to minimize too, since it forces entrants to be less efficient in allocating their own time since they have to block off more time to cover the n-standard deviations wait-time, which means they can’t be as efficient even if they get the fast queue since they didn’t schedule anything for that time. It may or may not be worth the extra overhead.

TeMPOraL 8y ago

> In the real world you won't have the same service time for both cases since you need to add in walking from the global queue to the individual registers. In all single-queue systems I've seen, this is solved by the cashier pressing the "register free" button before being finished with the previous customers. > You will end up with increased confusion from customers who always have to be on the lookout for next open spot I find it, and I find it pretty clearly, for the opposite to be true. In single-queue system, I can literally sleep-walk and read books/browse social media the entire queue up until the point I reach the front end, where I only need to pay attention to the sign telling me to which register to go. With multiple queues, I feel the need to pay attention to whether or not another register is opening, or whether or not one of the customers in front of me has high handling time risk - so that I can switch queues early on.

entity345 8y ago

> You will end up with increased confusion from customers who always have to be on the lookout for next open spot That simply does not happen in the real world.