How can I garbage collect these particles? I have no idea how garbage collection works, so sorry if it’s a dumb question
for _, particle in grenade:FindFirstChild("VFX"):GetDescendants() do
if particle:IsA("ParticleEmitter") then
particle:Emit(particle:GetAttribute("EmitCount"))
end
end
You don’t.
Garbage collection referes to reclaimation of memory that was allocated but is referenced no more, therefore it may be freed for further use. When LuaVM no longer holds a strong reference over an object and the object is disconnected from the data model, the engine garbage collector may clear it. I recommend reading Hexcede’s post for more details.
Garbage collection and memory leaks are terms that are in Luau usually referred to in conjunction with something tangible, something Luau works with, like Instances, RbxScriptConnections, tables, functions, coroutines etc.
The particles are handled by the engine for the most part. All a ParticleEmitter provides are sets of properties and functions to control their appearance and flow, but the particles themselves cannot be referenced, they do not appear as objects in workspace, and they are not returned by any provided functions.
Particles spawn, stay around for their lifetime, and vanish. Don’t worry about the memory. They are not invasive. If you study memory usage in dev console you’ll see that it slightly increases with the number of particles but hardly in the overall scheme. They can much more likely impact rendering than cause memory issues.
Apparently the allocated memory stays occupied until the emitter is destroyed. It may increase but not decrease, even if we :Clear().
For your specific question regarding particle emitters in Roblox, there are a few key points to understand:
Automatic Garbage Collection: Lua’s garbage collector automatically takes care of freeing memory for objects that are no longer reachable or used. This means you don’t need to manually delete objects like you might in languages without garbage collection. Once there are no more references to an object (in this case, a ParticleEmitter), Lua’s garbage collector will eventually collect it.
ParticleEmitters and Memory: When you use particle:Emit(), you’re instructing the particle emitter to emit a certain number of particles. The particles themselves are managed by the Roblox engine, and you don’t have direct control over their memory management. Once emitted, the particles will follow their configured behavior (lifetime, speed, etc.) and will be automatically cleaned up by the engine when they expire or when the emitter is destroyed or collected.
To ensure that your particle emitters and their particles don’t leak memory or cause performance issues, follow these guidelines:
Ensure Emitters are Child of a Destroyed Object: If the particle emitters are children of an object (like your grenade object) that gets destroyed, they will also be destroyed and eligible for garbage collection. Make sure you’re calling grenade:Destroy() or similar on the parent object when you’re done with it.
Remove References: Make sure there are no lingering references to the particle emitters or their parent objects in your script or elsewhere. This includes tables, global variables, or connections that might keep a reference to the object.
Manual Cleanup: While Lua handles garbage collection automatically, you can suggest to the Lua garbage collector to run by using collectgarbage("collect"). However, this is generally not recommended or necessary in Roblox development, as it can cause performance hiccups and the Roblox engine is optimized to handle its own garbage collection efficiently.
grenade:Destroy() -- This destroys the grenade and all its descendants, including particle emitters.
Thank you both for your detailed answers! I understand a lot better now 
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