Re: Ever-Increasing Memory Usage in 5.0

[Chris Marrin <chris@...>]

Daniel Silverstone wrote:
> ...
> When I last worked on a game engine, we would force a garbage-collect
> once per second which was less irritating than every frame but often
> enough to keep memory use down. But we weren't using Lua so I don't know
> how Lua would behave in this instance.

One of the most incredible things about Lua 5.1 is its incremental GC. 
We have a rendering engine which uses Lua, so we have a rendering loop 
that runs at ~60fps. After each loop I added this:

    double ct = getCurrentTime();
    lua_gc(myState, LUA_GCSTEP, 10);
    ct = getCurrentTime() - ct;

The resultant ct (collect time) is close to 0% when the system was at 
idle and rarely got above 1% of total frame time at high load. I also 
monitored memory usage:

    int memused = lua_gc(myState, LUA_GCCOUNT, 0);

and found that memory would peak after some high load frames and then 
take around 2 seconds or so (120 frames) to get back to its quiescent 
state. This is great for any real-time system like this. Memory usage is 
kept under control, but GC never affects frame rate and therefore 
animation stays smooth.

So, switch to 5.1 :-)

--
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