Paper: max-chunk-load-threads

[Decme]

We have min-chunk-load-threads, do we need a maximum limit too? I've read alarming reports that some admins have been asked by their server hosts to reduce the amount of CPU power they are using. Having a limiter to the number of threads the async chunkloader uses could help with this.

[aikar]

We actually dont have a min anymore, that setting was removed.

However there is a max currently but it's done by JVM parameter

-Dpaper.maxchunkthreads=2

However, I don't think this will solve the hosts 'concerns'. Hosts never expected a process to use more than 1 - 1.5 cores of processing, but now they can with just world gen threads.
Even if we limit world gen to 1 thread making all worlds share it, that still gets it up to 2-3 cores worth of potential.

I guess I can add options to disable async chunk gen, and limit async chunk gen to a single thread, to put some caps on usage, and expose the load thread as a yaml config instead of system.

I think I'll also add an option for server hosts to set a system environment variable declaring its a shared host to set some defaults too.

[aikar]

But considering mojang is going down this same road, hosts need to prepare for this....

[aikar]

New options have been added to paper.yml
you can disable thread per world and reduce load threads to say 2.

Server hosts: See https://github.com/PaperMC/Paper/commit/a64b0952cb58f950e77167530308bcc3b6234c1b for methods to automatically force settings adjustments for your clients