Force Garbage Collection

Development Programming & Scripting
1

Hey,

So I’ve got a game in which a lot of actors are spawned, at a rapid rate. They also get destroyed almost as fast.
Since the latest Rocket upgrade, I seem to get a massive slowdown after about a minute, until a garbage collection happens. We’re talking of an fps drop from 120 fps to ~20fps, then straight back up to 120. Looking at the object count at the top of the screen, we’re talking going from ~300k to ~450k until the gc comes into effect.

I can force a garbage collection by using the console command, ‘OBJ GC’, but I can’t find a way to automate that through script. When I execute a console command, using OBJ GC, I just get a crash.

Is there any way to modify to GC rate? Preferably through just script.

Cheers,
Chris

2

Dear Chris,

The title of your thread, in World.h :slight_smile:

#Running When You Want

You could run it on a timer :slight_smile:

//void ForceGarbageCollection( bool bFullPurge = false ); //I use True
GetWorld()->ForceGarbageCollection(true);

#Crashes Solution → IsVallidLowLevel()

For actors that could be garage collected,

you can do this check

if(!Actor->IsValidLowLevel()) return; //dont try to access null or is-being-destroyed
Actor->DoStuff();

I find that catches a lot of what would otherwise be crashes when GC has just been forced

Rama

1 Like
3

You should never ever allocate and destroy anything rapidly “At a rapid rate” - If you are doing this then you should be using a spare list. And reusing those allocations.

Also you cannot simply force a garbage collection any time you want. There are specific points in the update loop where it is possible.

GEngine->ForceGarbageCollection();

This occurs after all the tick groups have run. so NO you cant run it on a timer. You tell it to ignore its heuristic, and force a GC at the end of the current frame.

2 Likes
4

There’s a handy console command that will force garbage collection every frame. This is really useful for testing to make sure that you didn’t muck up your memory management:

gc.CollectGarbageEveryFrame 1
6 Likes
5

Why no one suggested to use object pooling?

If you spawn and destroy these actors really fast then you have to use object pooling

6

It was mentioned in the 3rd comment.