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Re: Load balancing and load determination



> On 30 Oct 2018, at 12:53, Jim Jagielski <jim@xxxxxxxxxxx> wrote:
> 
> As some of you know, one of my passions and area of focus is
> on the use of Apache httpd as a reverse proxy and, as such, load
> balancing, failover, etc are of vital interest to me.
> 
> One topic which I have mulling over, off and on, has been the
> idea of some sort of universal load number, that could be used
> and agreed upon by web servers. Right now, the reverse proxy
> "guesses" the load on the backend servers which is OK, and
> works well enough, but it would be great if it actually "knew"
> the current loads on those servers. I already have code that
> shares basic architectural info, such as number of CPUs, available
> memory, loadavg, etc which can help, of course, but again, all
> this info can be used to *infer* the current status of those backend
> servers; it doesn't really provide what the current load actually
> *is*.
> 
> So I was thinking maybe some sort of small, simple and "fast"
> benchmark which could be run by the backends as part of their
> "status" update to the front-end reverse proxy server... something
> that shows general capability at that point in time, like Hanoi or
> something similar. Or maybe some hash function. Some simple code
> that could be used to create that "universal" load number.
> 
> Thoughts? Ideas? Comments? Suggestions? :)

What problem are you trying to solve? Broadly, I think they best you can do is ask the backends to include a response header indicating their current appetite for more connections.

- Mark