Priority of background loading thread.
Lets you control how long it takes to load data asynchronously vs performance impact on the game while loading in the background.
Asynchronous load functions that load objects (Resources.LoadAsync, AssetBundle.LoadAssetAsync, AssetBundle.LoadAllAssetAsync), scenes (SceneManager.LoadSceneAsync) do data read and deserialization on a separate background loading thread and object integration on a main thread.
Integration depends on an object type and for textures, meshes means uploading data to the GPU, audio clips prepare data for playing.
To avoid hiccups we limit integration time on a main thread depending on backgroundLoadingPriority value:
- ThreadPriority.Low - 2ms
- ThreadPriority.BelowNormal - 4ms
- ThreadPriority.Normal - 10ms
- ThreadPriority.High - 50ms
This is a maximum time all asynchronous operations can spend within a single frame on a main thread.
Background loading thread uses backgroundLoadingPriority directly.
The Profiler marker Application.Integrate Assets in Background lets you optimize background loading.
using UnityEngine;
public class ExampleScript : MonoBehaviour { void Example1() { // Load as much data as possible, as a result frame rate will drop. // Good for fast loading when showing progress bars.
Application.backgroundLoadingPriority = ThreadPriority.High; }
void Example2() { // Load data very slowly and try not to affect performance of the game. // Good for loading in the background while the game is playing.
Application.backgroundLoadingPriority = ThreadPriority.Low; } }
Additional resources: ThreadPriority enum, AsyncOperation.priority.