The documentation about the ordering of RunService events is incorrect

Bug Reports Documentation Issues
,
#1

title self explanatory

Everything is correct, except the part where it says that .PostSimulation runs before .Heartbeat, when the opposite is true:
image

In microprofiler, it appears that .PostSimulation runs after .Heartbeat:

image
image1198×561 177 KB

The code to reproduce this: (localscript in StarterPlayer)

local RunService = game:GetService("RunService")

local function logevent(eventName)
	debug.profilebegin(eventName)
	for i = 1, 10000 do local a = Random.new():NextUnitVector() * math.random(100) end -- junk work to lengthen the frame
	
	debug.profileend()
end

-- it doesnt matter in which order the events below are connected to a function

RunService.PreRender:Connect(function()
	logevent("PreRenderEvent")
end)

RunService.RenderStepped:Connect(function()
	logevent("RenderSteppedEvent")
end)

RunService.Stepped:Connect(function()
	logevent("SteppedEvent")
end)

RunService.PreAnimation:Connect(function()
	logevent("PreAnimationEvent")
end)

RunService.PreSimulation:Connect(function()
	logevent("PreSimulationEvent")
end)

RunService.PostSimulation:Connect(function()
	logevent("PostSimulationEvent")
end)

RunService.Heartbeat:Connect(function()
	logevent("HeartbeatEvent")
end)

The correct ordering of the events according to the microprofiler, are:

  1. RenderStepped
  2. PreRender
  3. PreAnimation
  4. Stepped
  5. PreSimulation
  6. Heartbeat
  7. PostSimulation

Repro file: runservice ordering doc issue repro.rbxl (55.1 KB)

Page URL: https://create.roblox.com/docs/studio/microprofiler/task-scheduler#scheduler-priority

1 Like
#2

Already tried fixing this with a previous PR, but it’s the code itself that is incorrect. PostSimulation is intended to run before Heartbeat, even though the opposite is currently true. I believe this is being worked on internally.