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Comment by sorokod | Hacker News Reader

When unrestricted, event driven systems don't have a well defined overall state or consistency.

Avoid if you have rules that depend on a system "state"

Having said that, toy systems aside, almost all systems require reasoning of their overall state at some point, so in general - avoid.

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This is just software engineers failing to have taken classic basic engineering courses during their education. These are basic problems that control systems deal with and you have things like PID that to other engineering disciplines are obvious.

The amount of times I've seen software clearly want to have a form of PID controller and fail to realize that such a thing even exists are countless.

Do you have any recommendations for resources that map control theory to web services? I find the idea really interesting. I have two questions though

How well do controllers work with non-numerical inputs? I would assume the usual use cases involve numerical data from sensors.

Does it work well with applications where the importance of availability supersedes consistency? When I hear controller, I can’t help but think single point of failure

You might want to apply it to the scaling of web services rather than the fine details of the application itself. I think you would want to focus on the areas where you can reduce your variables to simple numerics.

That does make sense, but isn’t that what container orchestration services do for you?

Not very effectively yet, in my experience. Also, "throw more compute at it" is much simpler in complexity to something like PID. We don't have good orchestration yet for automating changes of multiple variables.

/s orchestrating workloads on 10^5 hosts.

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