Getting the count of a component in World?

[late burrow]

How can we get the count of a certain component in the World from the main thread (normal Monobehaviour)?

[tardy flame]

You can create query (remember that it's IDisposable) from EntityManager and use CalculateEntityCount

[late burrow]

thanks! I think the new API has changed that to GetAllEntities() ?

[tardy flame]

no

that's like 10000 times more epxensive method

[late burrow]

yeah the docs says it creates a sync point..

but EntityManager doesn't have any CalculateEntityCount function

https://docs.unity3d.com/Packages/com.unity.entities@1.0/api/Unity.Entities.EntityManager.html

maybe it's been deleted in the 1.0.0?

[ocean patio]

the query should have it

you create an EntityQuery with the thing you're interested in first

[late burrow]

so like

int sum = 0;
for (var i = 0; i < World.All.Count; i++) {
    using var query = World.All[i].EntityManager.CreateEntityQuery( typeof(FloatAroundComponentData) );
    sum += query.CalculateEntityCount();
}
``` right?

seems none of the methods here have sync point, nice

[tardy flame]

whatever is it you are doing here is not really a good practice

is your game Mono based?

[late burrow]

no game. just benchmarking

wanted to get the count of all FloatAroundComponentData components

[late burrow]

btw that seems to work but halved the fps

[tardy flame]

if you are just benchmarking, you might just want to create your own world

[ocean patio]

creating entity queries is not free

also, a detail, but typeof(FloatAroundComponentData) will create a temp managed array iirc, try with ComponentType.ReadOnly<FloatAroundComponentData>()

also CalculateEntityCount itself is not free, actually

[late burrow]

ah didnt know that. thanks!

[ocean patio]

im not sure, look at the function you use 🙂

[tardy flame]

nah, it's best to just use EntityQueryBuilder

Array aloc is fine

Temp*

while overload is mentioned is actually creating a GC array

[ocean patio]

well potato potato it's all very similar in the end 😄

you can also see entity counts using some of the entities inspectors

[ocean patio]

well thats what i meant

[tardy flame]

yeah, in the end it's all same

but I suggested the most recent and mainstream API for that

[late burrow]

this made the results ~1.3 times faster on average (3 times)

I guess it can't go any faster than this

thanks @tardy flame and @ocean patio 🙂🙏

[late burrow]

Update

I used a static field inside my ISystem where I instantiate entities with that prefab and obviously it worked lightning fast. if anyone's in the same situation and can take advanatge of that, it's the fastest approach I found

[tardy flame]

static field of what?

[late burrow]

the count

i was trying to get the count of a certain component

so I just hacked my way by doing that

[tardy flame]

well, sure. But in real development it'd be anti-pattern and not burst compatible

[late burrow]

it's just for benchmarking purposes

in real scenario the component may be converted by a baker , not necessarily instantiated by another system

so yeah this will work for scenarios where you know that this component is only gonna be instantiated by a certain ISystem

[tardy flame]

idk what exactly you are benchmarking

but feels like you are doing it wrong

😅

[late burrow]

man i feel the same way lol

i mean the results are OK

[tardy flame]

there's a test framework

for benchmarking

[late burrow]

but yeah there has to be a more super-fast general purpose way that im missing

[late burrow]

I really wanna avoid using editor-only assemblies with this

[tardy flame]

    "com.unity.test-framework": "2.0.1-pre.18",
    "com.unity.test-framework.performance": "3.0.0-pre.2",

[tardy flame]

they support build testing too

it's using NUnit as base

and is nicely integrated with engine

[late burrow]

but i mean in the end it's not gonna outperform a static field so why bother

that seems to be meant for bigger tests

[tardy flame]

outperform what?

[late burrow]

mine is too tiny for that

[tardy flame]

tests are done to compare something

in pure environment

[late burrow]

the static field that I mentioned above with a big UPDATE h2 header

[tardy flame]

well

that doesn't say anything about what is being tested

[late burrow]

ah, that, well thats kinda irrelevant, but its this:
a Spawner spawns a prefab every n seconds.
the prefab has a component that makes the LocalTransform move to a random location, randomly

the component count I wanted to measure was the moving one's

the test performance is FloatingAroundComponent count per DeltaTime milliseconds (frame time)

the more the components, the less the frame time

the benchmark is to see how much

[tardy flame]

is it jobified?

[late burrow]

yup. with the new IJobEntity that auto generates the source

[tardy flame]

jobified stuff is not that trivial to benchmark

[late burrow]

the spawner is using plain query , the mover/floater is using IJobEntity

I tested with GameObject and got to ~2,100 spawned cubes floating around. with ECS it reached up to ~45,000

the number is when the fps hits 60