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From Christopher Schultz <ch...@christopherschultz.net>
Subject Re: [OT] Tomcat Online Parameter Setting/Tuning
Date Wed, 13 Mar 2019 01:25:36 GMT
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Supun,

On 3/12/19 12:05, Supun Abeysinghe wrote:
> I am working on a project where the parameters of the tomcat server
> (e.g. MaxThreads, MinSpareThreads, MaxSpareThreads etc.) for a
> given web application is auto-tuned using a machine learning
> technique by looking at the runtime characteristics (e.g. workload
> characteristics, current performance etc.).

I'm kind of curious about this. Is this Nest[1] for Tomcat?

My experience is that traffic is bursty. That means that it's hard to
predict when you'll need more resources -- like threads, one of the
only things you can really tune at runtime. When you need them, you
want them NOW, not when some algorithm finally gets around to
detecting the burst of traffic you know has already begun.

Since the server must be planned for X number of threads at peak
volume, why not simply always run with X threads? There is really no
penalty for leaving threads unused, other than "wasted" memory... that
you would need if you needed the threads, anyway. It's not like you
can use that memory for anything else, because you're going to need it
at peak-load time.

If you are interested in doing ML for capacity-tuning, I'd look more
toward auto-scaling of *instances* rather than the resources being
used by one single Tomcat instance. If I can scale-down my VMs
deployed into, say, AWS, then I can save *real money* by scaling-back
during low-load times and learning about trends to pre-scale things
before e.g. the Friday-night rush or whatever happens to be "peak
volume" for my particular use-case.

- -chris

[1] https://nest.com/thermostats/
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