Using a Coroutine to Distribute Loop Processing Over Several Frames?

Unity Engine
1

Hi folks, I’m trying to figure out how to spread loops over large sets over time so they don’t suck up too many fps. Here’s what I’ve come up with.

Is there a known better way or any other comments on how to approach this problem?

Anyone have a better way to handle pauses? Perhaps allow completion of the coroutin on pause and then restart on unpause? The current method works and when paused I see a huge increase in FPS, which is good.

IEnumerator LoadBalancedLoop() {
	float breakTime;
	int i = 0;
	int length = 2000000; //would be Array.Length-1;
	float maxTimePerStep = 1/1200f;
	while (true) {
		//isSimPaused is my own pause bool, means calculations not needed
		while (!isSimPaused  Time.realtimeSinceStartup < breakTime) {
			if (i % 100000 == 0) {
				//Debug.Log is slow enough to alter results, so turn off except for debugging
				Debug.Log(i+" indexed at RealTime:"+Time.realtimeSinceStartup);
			}				
			i++;
			if (i > length) {
				//reached end of array. Reset and get out
				//or could start over and not break
				i = 0;
				break;
			}
			//would operate on array[i] here
		}
		yield return null;
	}
	yield return null;		
}
2

It’s better just to use threads.

–Eric

3

Oh, that would be nice. I thought unity was not thread-able though. I should mention I am using things like Raycast inside the loop.

4

Yeah, Raycast wouldn’t work since the Unity API is not thread-safe. You can use any thread-safe Mono functions in threads though.

–Eric

5

As I thought, thanks. It’s possible I could get rid of the Raycasting dependency in this case, but meanwhile…

I just tried implementing my concept in a fairly complex loop (testing Line-of-sight for each and every Entity in the scene). This has loops inside loops and is hard to deconstruct as I had it above. I came up with a less pretty but easier to use method.
Again, anyone run into trouble doing it this way?

public IEnumerator LoadBalancedUpdateView ()
{

	float maxTimePerStep = 1 / 1200f;
	float breakTime = Time.realtimeSinceStartup + maxTimePerStep;
	bool didYield = false;
		
	while (true) {
		if (LevelManager.isSimPaused) {
			yield return new WaitForSeconds(1);
		}
		if (LevelManager.isSimPaused) {
			// this looks weird but takes advantage of the fact that the
 			// loop picks up here after the yield, so we 'do not pass go' and
			// go back to top and check against isSimPaused				
			continue;
		}
                //some loops within loops here and at a likely spot I put in this.
                //in fact I think these could be sprinkled through the loops just after likely bottle-necks
  		foreach (thing in these) {
                   foreach(foo in bar) { 
			if (Time.realtimeSinceStartup > breakTime) {
				didYield = true;
				yield return null;
			}

			if (didYield) {
				//picking up again after a yield 
				//reset the time we should return from;
				breakTime = Time.realtimeSinceStartup + maxTimePerStep;
				didYield = false;
			}