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Load balancing and load determination


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? :)