Clarifications/Questions on memory leaks

[0xD00TD00T]

I have a few questions about what does and does not cause memory leaks.

1. If you set up a new variable in a function and have it store an object, what happens to that reference when the function is done running?

e.g

function someFunction()
    local object = workspace.Object
end

When that function has finished running, what happens to that reference? Is it stuck in memory, causing a leak? Or does it get cleaned up?

2. Does overwriting a Connection cause a leak?

For example,

conn = game.Players.PlayerAdded:Connect(function(plr)
    -- do something
end

conn = workspace.Object.Touched:Connect(function(hit)
    -- do something else
end

Is this a leak, or is the first connection cleaned up/overwritten?

3. If you have a CharacterAdded function connected to a player, does it cause a leak when the player leaves?

[DrKittyWaffles (x64dbg)]

@0xD00TD00T

If you set up a new variable in a function and have it store an object, what happens to that reference when the function is done running?

The variable is “destroyed” in sense. The object reference should become garbage collected and memory will be “freed”

@0xD00TD00T

Does overwriting a Connection cause a leak?

No.

@0xD00TD00T

If you have a CharacterAdded function connected to a player, does it cause a leak when the player leaves?

All connections on an object are destroyed when the object is destroyed. So when a player leaves all of the connections that are connected to them (and are not referencing anything that might keep them alive such as themself) then you can expect there to be no memory leak.

Just be careful to not do anything that can happen here:

PSA: Connections can memory leak Instances!

Preface I’ve seen several experienced developers not knowing this, or not having a full understanding of what’s going on, so I thought I’d write a dedicated post on the issue of accidentally leaking Instances (so that they are not GCed even when there are no references to them) through lingering event connections. What circumstances cause a leak do -- All good, this part will be GCed just fine local p = Instance.new('Part') p.Touched:connect(function() print("Touched") end) end do -- O…

[sjr04 (uep)]

@0xD00TD00T

function someFunction()
    local object = workspace.Object
end

When that function has finished running, what happens to that reference? Is it stuck in memory, causing a leak? Or does it get cleaned up?

Since local variables cease to exist when their scope ends, that reference will go away

@0xD00TD00T

2. Does overwriting a Connection cause a leak?

For example,

conn = game.Players.PlayerAdded:Connect(function(plr)
    -- do something
end

conn = workspace.Object.Touched:Connect(function(hit)
    -- do something else
end

Is this a leak, or is the first connection cleaned up/overwritten?

no

But the connection is still connected

@0xD00TD00T

3. If you have a CharacterAdded function connected to a player, does it cause a leak when the player leaves?

no