Canvas adds a ton of new optimizations to the game, including AI optimizations, farm optimizations, and large-scale threading optimizations
Canvas' most significant optimization is Multithreaded
Dimension Ticking(MDT), which turns each world into its
own mini-server. NMS has a BlockableEventLoop class,
which acts as a scheduler for ticking repeated tasks on
a single thread. The main performance drawback of normal
servers are the fact that it ticks almost entirely on a
single thread. Folia attempts to fix this bottleneck by
threading the server in regions, which has caused
numerous issues like breaking plugin compatibility,
disabling numerous features and commands, and tons of
bugs and crashes. To fix this, Canvas attempts at making
the server combine work using multiple threads for
ticking 1 single server.
The main thread tick loop has been stripped of most
logic having to do with World ticking, since each world
now is an extension of a TickLoopThread, which is an
abstract implementation of the NMS BlockableEventLoop
that handles most of the logic for ticking each world.
After startup, each world(including ones added by plugins and datapacks) gets booted into its own thread to begin ticking, and at that point each world ticks independently and is completely split off from the main thread, similar to Folias region logic, but instead of a thread pool executing the ticks, it processes their own tick on their own.
Upon a player joining the server, the main thread will handle the joining logic like creating the player, building the playerdata, etc. Once its ready for "gameplay" stages(or the player is now in runtime), the packet handler is sent to its currently owned world to be processed, meaning each world will handle its own players connections/disconnections. If the world is crashing/lagging, the main thread will be used as fallback until the world thread is stable again.
In the end, this essentially makes each world its own server, interacting with each other and working concurrently to provide a huge boost in performance. Some users have seen immense improvements in MSPT, and even with hundreds of players, it can maintain 20TPS.
There are numerous optimizations added by Canvas in relation to entities, like the following:
- Async Pathfinding
- Experience Orb optimizations
- Entity Goal optimizations
- Entity Pathfinding optimizations
An odd part of Minecraft pathfinding is its nature to continue attempting to pathfinding despite the entity being in an enclosed space or crammed with other entities, making it unable to move, despite the pathfinder still trying to. This causes unnecessary processing that takes up a lot of server resources fast for mob farms like Enderman farms. To fix this, Canvas pre-calculates the entities currently intersecting with its bounding box, meaning if its crammed with a configurable amount of entities(default 2, which means its crammed with a lot of entities since normally entities shouldnt be intersecting with each others bounding boxes), the pathfinder will be turned off for that tick, saving a lot of unneeded resources on mob farms.
Entity goals have also been optimized, reducing the rates of strolling and extremely expensive mob goals by a configurable amount to allow for less time spent on goal ticking, while also making it still look natural.
With giant XP farms, a lot of XP orbs are created and get "merged" by spigots XP orb optimization. This optimization works, but only to a specific degree. It does "merge" the orbs, but it mostly just moves the orbs to the same location and thats it, which doesnt do as much in the long run. There is now a configuration that allows for better merging of these orbs, allowing for making the entity truly into a single entity with the combined XP count of all the orbs. This reduces the amount of entities processed on the server and client, often times improving framerates in heavy mob farm situations.
Generally, at least 3-4 more threads than you normally would to account for the new WorldTicker threads.
Folia is more experimental software, and has a ton of bugs. Canvas is more of an in-between of Paper and Folia, bringing Folia-like optimizations but to a less severe degree and reworked to be more plugin-compatible and more performant. Plugin compatibility is a lot better than Folia, just because of the nature of how the both of them work. However, the plugin does have to be thread-safe in most situations to be considered compatible with Canvas.
