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How can I optimize Lua.IsTrue() on Update()?

Posted: Thu Jul 22, 2021 8:47 am
by vcesauron
Disclaimer: I am still a beginner at profiling code, so pardon me if I say anything stupid xD

Our game is suffering from intermittent freezes every other couple of seconds. After taking a look at the CPU Profiler and the Call Stack, blocks of GC.Alloc() and GC.Collect() caused by Lua.IsTrue(string) seem like the "culprit".
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gc2.png (194.01 KiB) Viewed 391 times
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The game relies on checking for many Lua conditions several times per frame, and the way I do it currently is calling Lua.IsTrue(condition) every time I need to check the value of condition.

I created some sort of manager to limit the number of calls to this function per frame since many of those aren't frame-critic, and I did reduce the number of calls per frame from +20 to 5 (a value chosen by me), but it still keeps causing freezes.

How can I keep checking for Lua conditions while avoiding the freezes?

Re: How can I optimize Lua.IsTrue() on Update()?

Posted: Thu Jul 22, 2021 9:05 am
by Tony Li
Hi,

Avoid checking Lua.IsTrue() continually on Update().

If you're checking Lua.IsTrue() on Update(), you're using polling. It's much more efficient to make your code event-driven.

For example, if you want to know when a variable "X" exceeds 10, write a C# method IncrementX(), like:

Code: Select all

public void IncrementX()
{
    int x = DialogueLua.GetVariable("X").asInt;
    x++;
    DialogueLua.SetVariable("X", x);
    if (x >= 10)
    {
        // Invoke some event here
    }
}
You can call that method in a C# script or in Lua (e.g., in a conversation node's Script field) by registering it with Lua.

For another example of event-driven checking, examine the "Shoot 5 Enemies" quest in DemoScene2. The Enemies' IncrementOnDestroy components increment a variable and then invoke an OnIncrement() UnityEvent. The scene only checks if the variable is >= 5 in this OnIncrement() event. It doesn't check every frame.

If that's not possible, switch the Dialogue System to use NLua.

Re: How can I optimize Lua.IsTrue() on Update()?

Posted: Thu Jul 22, 2021 9:22 am
by vcesauron
I'm gonna try the event-driven approach first.
Because I'm using booleans, most of the checks are Variable["X"] == true, but I'll try to apply the same logic.

If it doesn't work, I'll try NLua.

Thanks for the quick response!

Re: How can I optimize Lua.IsTrue() on Update()?

Posted: Thu Jul 22, 2021 9:26 am
by Tony Li
Glad to help!