Session locking in Roblox: what ProfileService-style modules do and why

Updated 2026-11-09 · Roblox and game developers · by CyberMax

Copy-paste code

The core of a session lock (inside UpdateAsync)

Copylocal SESSION = game.JobId ~= "" and game.JobId or "studio"
local STALE = 30 * 60 -- a lock older than 30 min is treated as abandoned

-- returns the profile if this server now owns it, or nil if another live server does
local function acquire(store, key)
	local owned
	local ok = pcall(store.UpdateAsync, store, key, function(old)
		old = old or { data = { coins = 0 } }
		local lock = old.lock
		if lock and lock.session ~= SESSION and os.time() - lock.at < STALE then
			return nil -- someone else holds it: change nothing
		end
		old.lock = { session = SESSION, at = os.time() }
		owned = old
		return old
	end)
	return ok and owned or nil
end

local function saveAndRelease(store, key, data, release)
	pcall(store.UpdateAsync, store, key, function(old)
		if not old or not old.lock or old.lock.session ~= SESSION then return nil end -- lost the lock: don't write
		old.data = data
		old.lock = (not release) and { session = SESSION, at = os.time() } or nil
		return old
	end)
end

Good to know

If acquire returns nil, wait a few seconds and retry; the other server usually releases the lock when it finishes its PlayerRemoving save.

Autosaves refresh lock.at, so a server that crashes leaves a lock that goes stale after 30 minutes.

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