Lua performs automatic memory management.
This means that
you have to worry neither about allocating memory for new objects
nor about freeing it when the objects are no longer needed.
Lua manages memory automatically by running
a garbage collector from time to time
to collect all dead objects
(that is, objects that are no longer accessible from Lua).
All memory used by Lua is subject to automatic management:
tables, userdata, functions, threads, strings, etc.
Lua implements an incremental mark-and-sweep collector.
It uses two numbers to control its garbage-collection cycles:
the garbage-collector pause and
the garbage-collector step multiplier.
Both use percentage points as units
(so that a value of 100 means an internal value of 1).
The garbage-collector pause
controls how long the collector waits before starting a new cycle.
Larger values make the collector less aggressive.
Values smaller than 100 mean the collector will not wait to
start a new cycle.
A value of 200 means that the collector waits for the total memory in use
to double before starting a new cycle.
The step multiplier
controls the relative speed of the collector relative to
Larger values make the collector more aggressive but also increase
the size of each incremental step.
Values smaller than 100 make the collector too slow and
can result in the collector never finishing a cycle.
The default, 200, means that the collector runs at "twice"
the speed of memory allocation.
You can change these numbers by calling lua_gc in C
or collectgarbage in Lua.
With these functions you can also control
the collector directly (e.g., stop and restart it).