Crash with simple tower of 8k parts

Bug Reports Engine Bugs
#1

Im trying to replicate the bug in another thread, where spawned parts never arrive on client (unsuccessful :c).
But when I make a tower of 8k parts using unanchored parts with weld surface (I makejoints them on top of the tower, until theres 8k), the client:

  1. Took a long time to join (kind of expected)
  2. Crashed after a couple of seconds after I had jumped off the tower.

I dont think this should crash, given that 8k parts isnt that many, and it worked fine for a few seconds from joining.
Maybe its because theyre all connected by welds only, and theres a looong sequence of those parts until it finally reaches the anchored baseplate (that makes it not a very realistic situation).

1 Like
#2

It’s so weird that this is still an issue, even with the new WeldConstraint object… 7 years later.

Here are some steps to reproduce:

  • Make an array of parts, and weld them together. Have them weld in-order (using welds or weld constraints)
  • Unanchor them

The game will now crash. Happens even if it’s just a few parts.

Reproduction script 
local COOLDOWN_THRESHOLD = 0.5
local CAN_WELD_NON_ANCHORED = false
local CAN_WELD_THOSE_WITH_CONSTRAINTS = false

local LastFrame = os.clock()

local function MakeWeldRoot(Model : Model) : Part
	local Coordinate : CFrame = Model:GetBoundingBox()

	local RootPart : Part = Instance.new("Part")
	RootPart.Transparency = 1
	RootPart.Anchored = true
	RootPart.CanCollide = false
	RootPart.CanQuery = false
	RootPart.Size = Vector3.new(1, 1, 1) * 0.05
	RootPart.CFrame = Coordinate
	RootPart.Name = "Root"
	RootPart.Parent = Model

	Model.PrimaryPart = RootPart

	return RootPart
end

local function GetQueuedParts(ObjectArray : {[number] : Instance}) : {[number] : BasePart}
	local Parts : {[number] : BasePart} = {}

	for _, Object in ObjectArray do
		if Object:IsA("BasePart") then
			if not CAN_WELD_NON_ANCHORED and Object.Anchored == false then
				continue
			end

			if not CAN_WELD_THOSE_WITH_CONSTRAINTS then
				local HasConstraints = false

				for _, PotentialConstraint : Instance in Object:GetChildren() do
					if PotentialConstraint.ClassName:find("Constraint") then
						HasConstraints = true
						break
					end
				end

				if HasConstraints then
					continue
				end
			end

			table.insert(Parts, Object)
		end
	end

	table.sort(Parts, function(a, b)
		return a.Position.Magnitude > b.Position.Magnitude
	end)

	return Parts
end

local function WeldTwoTogether(RootPart : Part, Part : Part, WeldFolder : Folder)
	local NewWeld = Instance.new("WeldConstraint")
	NewWeld.Part0 = RootPart
	NewWeld.Part1 = Part
	NewWeld.Parent = WeldFolder

	Part.Anchored = false
end

local function WeldModel(Model : Model)
	local WeldFolder = Instance.new("Folder")
	local Objects = Model:GetDescendants()
	local Parts = GetQueuedParts(Objects)
	local RootPart = MakeWeldRoot(Model)

	WeldFolder.Name = "WeldConstraints"
	WeldFolder.Parent = Model
	
	local LastPart = Parts[1]

	for _, Part in Parts do
		if Part == LastPart then
			continue
		end
		
		WeldTwoTogether(LastPart, Part, WeldFolder)
		LastPart = Part

		if os.clock() - LastFrame >= COOLDOWN_THRESHOLD then
			task.wait()
			LastFrame = os.clock()
		end
	end

	RootPart.Anchored = false

	print(`Welded model in location "{Model:GetFullName()}"`)
end

WeldModel(script.Parent)

When done in studio, there is no error message or anything. Studio just immediately crashes.

Log file:
0.580.0.5800572_20230615T165820Z_Studio_A68C5_last.log (76.3 KB)

Log Preview 
... Truncated to show after all loading into place, so excludes what led up to opening the file

2023-06-15T16:58:31.786Z,11.786068,2b1c,6 [FLog::StudioUpdate3DView] PlaceSessionPluginWidgetsView; 3DView visibility before update: true, 3DView updatesEnabled before update: true
2023-06-15T16:58:31.836Z,11.836220,1e98,6 [FLog::Warning] Warning: 
⏱️ Loading Default Properties
2023-06-15T16:58:32.355Z,12.355273,2f58,12 [DFLog::HttpTraceError] HttpResponse(#472 000001BB20729480) time:456.0ms (net:62.8ms callback:0.0ms timeInRetryQueue:0.0ms)status:403 Forbidden bodySize:53 url:{ "https://apis.roblox.com/content-aliases-api/v1/universes/get-aliases?page=1&universeId=0" } ip:128.116.95.4 external:0 numberOfTimesRetried:0
2023-06-15T16:58:32.813Z,12.813197,5da0,6 [FLog::Warning] Warning: 
⏱️ Loading Default Properties
2023-06-15T16:58:32.892Z,12.892177,3604,6 [FLog::Output] 
🔎 Now watching for new instances
2023-06-15T16:58:32.938Z,12.938193,49c0,6 [FLog::Warning] Warning: 
âś… Default Properties has loaded!
2023-06-15T16:58:33.226Z,13.226150,2b1c,6 [FLog::StudioUpdate3DView] PlaceSessionPluginWidgetsView; 3DView visibility before update: true, 3DView updatesEnabled before update: true

No dump file was generated. The logs seem to not say anything about a crash.