On 10/30/2018 01:53 PM, Jim Jagielski 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? :) >
Hello, It seems that is exactly what https://modcluster.io/ does. - it has a Tomcat listener / JBoss AS (Wildfly) module that reports a worker-side calculated load number https://docs.modcluster.io/#_worker_side_load_metrics - httpd side is completely oblivious as to how the number was calculated, which worker used which load metric to calculate it etc, it just receives a number - httpd side dynamically configures mod_proxy balancers according to joining and leaving worker nodes - httpd side uses the load number to balance requests among healthy workers An obvious down side is that the worker must implement this mod_cluster logic. Implementations exist for JBoss AS/Wildfly/Tomcat, but we don't have one for Jetty for example. On the bright side, the protocol itself is dead simple. Disclosure: I am involved in the project. Cheers Michal Karm Babacek -- Sent from my Hosaka Ono-Sendai Cyberspace 7
