Packages/com.unity.entities/manual/aspects-intro

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Packages/com.unity.entities/manual/aspects-intro

https://docs.unity3d.com/Packages/com.unity.entities@latest/index.html?subfolder=%2Fmanual%2Faspects-intro.html

[vertxxyz]

Is there any overhead associated with having aspects? I assume they aren't free, will I run into issues if I have a lot of aspects?

Dani (A Unity DOTS developer):

Well, the cost of aspects are two fold. One is the runtime cost and the other is the iteration cost. (that doesn't mean you can't use em, just know when to!)

Let's start with the latter. Due to the nature of aspects, we have to do a lot of symbol analysis. This is expensive and so over time the more aspects you add the higher the chance of your project having loooong domain reload times. - So use with care. If you have like 50-100 aspects that shouldn't be much of an issue, the problem starts at higher scales.

Now back to runtime cost. Aspects themselves don't do anything that a user couldn't have done themselves. And for the simple case might produce faster code, as they do cache themselves and are properly updated. They even work in jobs.

The performance cost of Aspects is when you acquire to much access permission. Like say I have an aspect with 5 components, two of which are RW. Now I go in my job, but since every aspect is RW it means the two components now can't run parallel. Meaning the whole aspect has to block a previous job using the aspect to run the next.

Note, this isn't actually a problem of the aspect itself, more the pattern that it lends itself to. E.g. for solving that problem still with aspect, you could have a AttackDroneRO and AttackDroneRW. If you're only using the RO version, it works on as many jobs you want until the AttackDroneRW job comes.

That is to say. At runtime aspects have handwritten cached performance, but if you're not carefull with them, you might end up getting long job queues.