getgc

Returns every object (as a table) Roblox is currently holding alive - functions and userdata by default, plus one extra type if you provide the filter argument.

getgc(filter: string? | includeTables?): function | userdata | table? | string? | thread? | buffer?

Pass true to also include tables, or pass a type name ("thread", "string", "buffer", or "table") to also include values of that type. With no argument, the list only contains functions and userdata.

Most commonly used to find functions you cant find via any other method.

Parameters

The function takes a single optional argument that can be either form below. Pass one or the other - same arg slot, mutually exclusive.

Parameter	Type	Description
includeTables	boolean?	true adds tables to the result. false is equivalent to passing nothing.
filter	string?	One of "thread", "table", "string", "buffer" - case-sensitive. Adds every value of that type to the result.

Any other string, and any other arg type, will raise an error.

Returns

{function | userdata | thread | table | string | buffer} - Returns a table containing every live GC object that matches the requested set. The default set is functions and userdata; the filter argument adds to that set (does not replace it).

Call	Returns
getgc() or getgc(false)	functions + userdata
getgc(true) or getgc("table")	functions + userdata + tables
getgc("thread")	functions + userdata + threads
getgc("string")	functions + userdata + strings
getgc("buffer")	functions + userdata + buffers

Example

In a Roblox game, find the central game-data table by a couple of known keys - useful when no script ever hands you a direct reference to it.

Example 1

<<<<<<< HEAD
local gc = getgc()
=======
-- getgc(filter: string? | includeTables?): function | userdata | table? | string? | thread? | buffer?
>>>>>>> 50e30f53759b0538759af25c9b271514aa2c9290

Anticheats often set up an __index honeypot: a table that hands back a value for any key you check, even ones it doesn’t really have. Read keys with rawget so it can’t trick you.

That vector is most commonly aimed at Dark Dex (and its forks) - the moment Dex references any Instance, the honeypot fires and you get kicked.

They also may use a weak-table trap: a honeypot object is the only value in a __mode = "v" table, with nothing else referencing it. Garbage collection normally removes it from the table. If your getgc scan still references that object, it will stay => anticheat sees the object having a reference => anticheat kicks you. The check looks something like this:

while true do
    -- weak values: an entry clears once nothing else references its value
    local tracked = setmetatable({
        newproxy(), -- [1] an object a scanner shouldn't touch
        {}, -- [2] another object a scanner shouldn't touch
        {}, -- [3] this is a 'throwaway': once a GC cycle happens, it should also be collected
    }, {__mode = "v"})

    -- make junk until the throwaway is collected, forcing a GC cycle.
    -- this can hang if something references the throwaway,
    -- so in production - it's generally paired with a separate timeout detection.
    while tracked[3] do
        tracked[4] = string.rep("\0\0", 1024)
        tracked[4] = nil
        task.wait()
    end

    -- the GC cycle ran. if both tracked objects were collected, nobody held them
    if not tracked[1] and not tracked[2] then
        continue
    end

    -- a tracked object survived: something is referencing it
    warn("scanner detected") -- or just localplayer:Kick()
end

The entries inside the tracked table don’t have to be real game objects - a newproxy() or {} work too. So don’t keep references to objects from getgc - read what you need and don’t store them.