Interns with toasters: how I taught people about load balancers • Hacker News Board

Re: Interns with toasters: how I taught people about load balancers

#21

Post by BillinghamJ » Sun, Apr 22, 2018, 9:27 AM UTC

captn3m0 wrote: post #14

BillinghamJ wrote: post #11

I don't really see how this is an issue engineers need to be particularly wary of? Firstly, your typical load balancer doesn't work this way anyway. It will just keep feeding requests to the application hosts on a round robin or random basis. Most don't keep track of how busy each instance is. Secondly, any decent (HTTP/layer 7) load balancer will notice if an instance is returning exclusively 5xx errors and will sto…

AWS ELBs work this way. They offer more requests to clients with the shortest backlog

Do you have a link to any documentation mentioning this?

As far as I’m aware - using ELBs heavily day to day - it doesn’t maintain a backlog and simply distributes requests on a round robin basis the moment they come in. There is no queue of waiting requests I don’t believe. If the request can’t be fulfilled immediately, it is rejected.

Re: Interns with toasters: how I taught people about load balancers

#22

Post by grosjona » Sun, Apr 22, 2018, 9:28 AM UTC

That's why I like random load balancing. If each machine is powerful enough and can handle a few thousand users then the distribution averages out.

Smart load balancers are only really necessary if you have inefficient servers that can't handle more than 100 connections per second and they're difficult to get right.

If you toss a coin 10 times, you're much more likely to get >=80% heads than if you were to toss that coin 1000 times.

Re: Interns with toasters: how I taught people about load balancers

#23

Post by pulkitsh1234 » Sun, Apr 22, 2018, 9:30 AM UTC

Maybe some people dismissed her problem as 'impossible' because she didn't inform what kind of load balancing technique was the load balancer using?

  I suspect what happened is that they didn't understand the problem, and so resorted to ineffective means to steer
  the attention away from their own inadequacies.

^ This statement is kinda harsh.

Re: Interns with toasters: how I taught people about load balancers

#24

Post by mrgordon » Sun, Apr 22, 2018, 9:38 AM UTC

BillinghamJ wrote: post #12

rajacombinator wrote: post #8

Earlier quoted context omitted.

What kind of college teaches about load balancers?

If they’re not teaching about the most basic principles of building scalable systems, what is the point of doing a degree, or hiring people who have done a degree?

Several of the top CS programs specifically do not teach details like configuring a load balancer as with a proper background in computer science it is assumed that you can figure out the latest programming languages and the install instructions for popular software packages. It would thus be a waste of a very expensive degree as you could learn about configuring LAMP and a load balancer at a trade school instead of a theoretical research university.

No one hires MIT grads because they graduate with more extensive load balancer knowledge.

Re: Interns with toasters: how I taught people about load balancers

#25

Post by thinkingemote » Sun, Apr 22, 2018, 9:43 AM UTC

amingilani wrote: post #2

Who is Rachel and how do her short and simple stories always hit the front-page? They're interesting but I always think they're a little _too_ simple. I mean this entire thing can be summed up with: 500s (and other errors) are returned faster than processed requests. Load-balancers will find a misbehaving server's queue empty more often and give it all the requests

Good writing, good story telling skills. I read this the whole way through, and I usually just skim. So she is able to write in such a way to do that.

Now, the actual technical or learning content is lower than the usual articles of the same length but it was a pleasanter read.

Re: Interns with toasters: how I taught people about load balancers

#26

Post by foota » Sun, Apr 22, 2018, 9:44 AM UTC

grosjona wrote: post #22

That's why I like random load balancing. If each machine is powerful enough and can handle a few thousand users then the distribution averages out. Smart load balancers are only really necessary if you have inefficient servers that can't handle more than 100 connections per second and they're difficult to get right. If you toss a coin 10 times, you're much more likely to get >=80% heads than if you were to toss that…

This is true, but if you have a tighter tolerance on how much load each machine needs to be able to handle then you may be able to waste less resources.

Re: Interns with toasters: how I taught people about load balancers

#27

Post by eecks » Sun, Apr 22, 2018, 10:13 AM UTC

xorcist wrote: post #13

amingilani wrote: post #2

Who is Rachel and how do her short and simple stories always hit the front-page? They're interesting but I always think they're a little _too_ simple. I mean this entire thing can be summed up with: 500s (and other errors) are returned faster than processed requests. Load-balancers will find a misbehaving server's queue empty more often and give it all the requests

Light hearted introductions to work related stuff you might encounter is always a crowd pleaser. It makes for great lightning talk ideas too. However, it might be prudent to point out that these things will feature in the first chapter of any book on load balancing, as an example of the pros and cons of different load balancing methods: least connections, least load, round robin etc. (Sometimes I suspect picking up a…

Do you recommend any books in particular in this area? It's something I need to learn more about.

Re: Interns with toasters: how I taught people about load balancers

#28

Post by dqv » Sun, Apr 22, 2018, 10:27 AM UTC

amingilani wrote: post #2

Who is Rachel and how do her short and simple stories always hit the front-page? They're interesting but I always think they're a little _too_ simple. I mean this entire thing can be summed up with: 500s (and other errors) are returned faster than processed requests. Load-balancers will find a misbehaving server's queue empty more often and give it all the requests

I think it has to do with how much (quality) content she puts out there. She posts consistently, which helps build an audience. That audience posts her stuff to HN and also upvotes her posts when they see them on HN.

Re: Interns with toasters: how I taught people about load balancers

#29

Post by ajdlinux » Sun, Apr 22, 2018, 10:50 AM UTC

BillinghamJ wrote: post #12

rajacombinator wrote: post #8

Earlier quoted context omitted.

What kind of college teaches about load balancers?

If they’re not teaching about the most basic principles of building scalable systems, what is the point of doing a degree, or hiring people who have done a degree?

My university taught me the most basic principles of building scalable systems. It didn't teach me about setting up load balancers.

What it did teach me: locks, semaphores, mutual exclusion, the memory hierarchy, threading... the core concepts of concurrent and distributed systems that are independent of the specifics of running a large-scale web application.

Re: Interns with toasters: how I taught people about load balancers

#30

Post by mcbain » Sun, Apr 22, 2018, 11:01 AM UTC

vivaan wrote: post #5

amingilani wrote: post #2

Who is Rachel and how do her short and simple stories always hit the front-page? They're interesting but I always think they're a little _too_ simple. I mean this entire thing can be summed up with: 500s (and other errors) are returned faster than processed requests. Load-balancers will find a misbehaving server's queue empty more often and give it all the requests

apparently you aren't the first one to wonder that [1]. It is Rachel Kroll, an engineer at fb [2]. Good point about the summary. [1] https://news.ycombinator.com/item?id=13401293 [2] https://www.facebook.com/wogrammer/posts/1748187012080407:0

Recently left FB, in fact.

Which is important context for many of her posts in the last month or so.