batteries/manual_gc.lua

63 lines
1.9 KiB
Lua

--[[
"semi-manual" garbage collection
specify a time budget and a memory ceiling per call.
called once per frame, this will spread any big collections
over several frames, and "catch up" when there is too much
work to do.
This keeps GC time burden much more predictable.
The memory ceiling provides a safety backstop.
if exceeded it will trigger a "full" collection, and this will
hurt performance - you'll notice the hitch. If you hit your ceiling,
it indicates you likely need to either find a way to generate less
garbage, or spend more time each frame collecting.
the function instructs the garbage collector only as small a step
as possible each iteration. this prevents the "spiky" collection
patterns, though with particularly large sets of tiny objects,
the start of a collection can still take longer than you might like.
default values:
time_budget - 1ms (1e-3)
adjust down or up as needed. games that generate more garbage
will need to spend longer on gc each frame.
memory_ceiling - 64mb
a good place to start, though some games will need much more.
remember, this is lua memory, not the total memory consumption
of your game.
disable_otherwise - false
disabling the gc completely is dangerous - any big allocation
event (eg - level gen) could push you to an out of memory
situation and crash your game. test extensively before you
ship a game with this set true.
]]
return function(time_budget, memory_ceiling, disable_otherwise)
time_budget = time_budget or 1e-3
memory_ceiling = memory_ceiling or math.huge
local max_steps = 1000
local steps = 0
local start_time = love.timer.getTime()
while
love.timer.getTime() - start_time < time_budget and
steps < max_steps
do
collectgarbage("step", 1)
steps = steps + 1
end
--safety net
if collectgarbage("count") / 1024 > memory_ceiling then
collectgarbage("collect")
end
--don't collect gc outside this margin
if disable_otherwise then
collectgarbage("stop")
end
end