5 ms·

The maximum number of connections thing in HTTP/1 always makes me think of queuing theory, which gives surprising conclusions like how adding a single extra tel

The maximum number of connections thing in HTTP/1 always makes me think of queuing theory, which gives surprising conclusions like how adding a single extra teller at a one-teller bank can cut wait times by 50 times, not just by 2. However, I think the problem is the Poisson process isn't really the right process to assume. Most websites which would run afoul of the 2/6/8/etc connections being opened are probably trying to open up a lot of connections at the same time. That's very different from situations where only 1 new person arrives every 6 minutes on average, and 2 new people arriving within 1 second of each other is a considerably rarer event. [1]: https://www.johndcook.com/blog/2008/10/21/what-happens-when-you-add-a-new-teller/ https://www.johndcook.com/blog/2008/10/21/what-happens-when-...

amluto 2y ago
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- timewizard 2y ago
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  - efdee 2y ago
    [flagged]
  - arjie 2y ago
    Almost every web forum enters a phase where participants bring in their pet politics into unrelated discussions. Whether they last or not depends entirely on whether the flamebait/troll creates a large reply structure or a non-existent one. This is why shadowbans are more effective than large groups of people responding angrily. Or, to cite the Deep Magic: "don't feed the trolls".
    - timewizard 2y ago
      It's hacker news. If you cared about the plight of these people why not organize to do something about it? Or is this just finding suffering in the world and then personally capitalizing on it? I get the dynamic. I find it disgusting here, in particular.
- dgfitz 2y ago
  I find a lot of value in being able to get a water or a coffee, use the restroom, have sidebar conversations with fellow employees, begrudgingly attend meetings, or take a walk to stretch my legs for a minute and think, personally.
tome 2y ago
Can't it cut wait times by infinity? For example, if the arrivals are at 1.1 per minute, and a teller processes 1 per minute.
- hinkley 2y ago
  You've forgotten about banker's hours :)
  - dylan604 2y ago
    There was a discussion not tool long ago about modern banks still with archaic practices. I have accounts at two different banks, and if I make a transfer request before 1:45PT, it is counted as same day. That makes no damn sense to me why that's a limitation at all today. It's not like a human needs to look at it, but even so, why the 1:45PT cutoff? Is it because it is 4:45ET? Then why not list it as that? And why does a banking computer system care about timezones or bankers' hours at all. It's all just mind boggling lame
    - hinkley 2y ago
      I know my father sometimes had to take 1 am phone calls because the insurance industry runs a lot of batch processing overnight, when the systems aren't competing with OLTP traffic. Banking software may be built the same way.
    - lmm 2y ago
      > Is it because it is 4:45ET? Then why not list it as that? Because a lot of their customers are too stupid to understand timezones.
      - dylan604 2y ago
        I guess that's saying more about the left coast customers then, right? as all of the customers from the other time zones have to do the conversion.
hinkley 2y ago
And if memory serves if you care about minimizing latency you want all of your workers running an average of 60% occupied. (Which is also pretty close to when I saw P95 times dog-leg on the last cluster I worked on). Queuing theory is really weird.
- deepsun 2y ago
  Why 60%? I suppose if they are less than 1% then latency will be even less.
  - hinkley 2y ago
    Poisson could probably explain it elegantly, but he's not here, just us.
- atombender 2y ago
  Most analyses I've read say the threshold is around the 80% mark [1], although it depends on how model the distribution, and there's nothing magical about the number. The main thing is to avoid getting close to 100%, because wait times go up exponentially as you get closer to the max. Little's Law is fundamental to queueing theory, but there's also the less well-known Kingman's formula, which incorporates variability of arrival rate and task size [2]. [1] https://www.johndcook.com/blog/2009/01/30/server-utilization-joel-on-queuing/ https://www.johndcook.com/blog/2009/01/30/server-utilization... [2] https://taborsky.cz/posts/2021/kingman-formula/ https://taborsky.cz/posts/2021/kingman-formula/
  - hinkley 2y ago
    If you look at the chart in the second link, where does the wait time leave the origin? Around 60%. The first one is even worse; by 80% you're already seeing twice the delay of 70%. If I were to describe the second chart I'd say 80% is when you start to get into trouble, not just noticing a slowdown. I said minimize latency, not optimize latency.
    - deleted 2y ago

amluto 2y ago

[flagged]

timewizard 2y ago
[flagged]
- efdee 2y ago
  [flagged]
- arjie 2y ago
  Almost every web forum enters a phase where participants bring in their pet politics into unrelated discussions. Whether they last or not depends entirely on whether the flamebait/troll creates a large reply structure or a non-existent one. This is why shadowbans are more effective than large groups of people responding angrily. Or, to cite the Deep Magic: "don't feed the trolls".
  - timewizard 2y ago
    It's hacker news. If you cared about the plight of these people why not organize to do something about it? Or is this just finding suffering in the world and then personally capitalizing on it? I get the dynamic. I find it disgusting here, in particular.
dgfitz 2y ago
I find a lot of value in being able to get a water or a coffee, use the restroom, have sidebar conversations with fellow employees, begrudgingly attend meetings, or take a walk to stretch my legs for a minute and think, personally.

tome 2y ago

Can't it cut wait times by infinity? For example, if the arrivals are at 1.1 per minute, and a teller processes 1 per minute.

hinkley 2y ago
You've forgotten about banker's hours :)
- dylan604 2y ago
  There was a discussion not tool long ago about modern banks still with archaic practices. I have accounts at two different banks, and if I make a transfer request before 1:45PT, it is counted as same day. That makes no damn sense to me why that's a limitation at all today. It's not like a human needs to look at it, but even so, why the 1:45PT cutoff? Is it because it is 4:45ET? Then why not list it as that? And why does a banking computer system care about timezones or bankers' hours at all. It's all just mind boggling lame
  - hinkley 2y ago
    I know my father sometimes had to take 1 am phone calls because the insurance industry runs a lot of batch processing overnight, when the systems aren't competing with OLTP traffic. Banking software may be built the same way.
  - lmm 2y ago
    > Is it because it is 4:45ET? Then why not list it as that? Because a lot of their customers are too stupid to understand timezones.
    - dylan604 2y ago
      I guess that's saying more about the left coast customers then, right? as all of the customers from the other time zones have to do the conversion.

hinkley 2y ago

And if memory serves if you care about minimizing latency you want all of your workers running an average of 60% occupied. (Which is also pretty close to when I saw P95 times dog-leg on the last cluster I worked on). Queuing theory is really weird.

deepsun 2y ago
Why 60%? I suppose if they are less than 1% then latency will be even less.
- hinkley 2y ago
  Poisson could probably explain it elegantly, but he's not here, just us.
atombender 2y ago
Most analyses I've read say the threshold is around the 80% mark [1], although it depends on how model the distribution, and there's nothing magical about the number. The main thing is to avoid getting close to 100%, because wait times go up exponentially as you get closer to the max. Little's Law is fundamental to queueing theory, but there's also the less well-known Kingman's formula, which incorporates variability of arrival rate and task size [2]. [1] https://www.johndcook.com/blog/2009/01/30/server-utilization-joel-on-queuing/ https://www.johndcook.com/blog/2009/01/30/server-utilization... [2] https://taborsky.cz/posts/2021/kingman-formula/ https://taborsky.cz/posts/2021/kingman-formula/
- hinkley 2y ago
  If you look at the chart in the second link, where does the wait time leave the origin? Around 60%. The first one is even worse; by 80% you're already seeing twice the delay of 70%. If I were to describe the second chart I'd say 80% is when you start to get into trouble, not just noticing a slowdown. I said minimize latency, not optimize latency.
  - deleted 2y ago