I'm not seeing a performance increase with the Job System. Help

Diagnosing the issue

Vanilla code path (6 ms):

vanilla / deep profile, hierarchy view:

Jobified code path (10 ms):

As you can clearly see here, it's caused by:

• NativeArray read & write operations, which are super slow outside Burst-compiled jobs

• = transform.position

• transform.position =

• and few other minor operations, like casting, enumeration and List reading, all magnified by this huge 10k loop.

Which lines are causing the biggest problem? It's

 position[i] = zombieList[i].transform.position;

and

 zombieList[i].transform.position = position[i];

Fixing the issue

TransformAccess to the rescue. It fixes all the problems mentioned above and leaves you with the eternal one: "how to draw 10k moving meshes under 60fps". Which is a better problem to have (as it's arbitrary one).

 using System.Collections.Generic;
 
 using UnityEngine;
 using UnityEngine.Jobs;
 
 using Unity.Entities;
 using Unity.Mathematics;
 using Unity.Collections;
 using Unity.Jobs;
 
 using Random = UnityEngine.Random;
 
 public class TestSystem : MonoBehaviour
 {
 
     [SerializeField] GameObject _prefab = null;
     TransformAccessArray _transformsAccess = default(TransformAccessArray);
     NativeArray<float3> _velocities = default(NativeArray<float3>);
     public JobHandle Dependency = default(JobHandle);
 
     void Start ()
     {
         int numInstances = 10000;
         var transforms = new Transform[ numInstances ];
         _velocities = new NativeArray<float3>( numInstances , Allocator.Persistent );
         for( int i=0 ; i<numInstances ; i++ )
         {
             GameObject instance = Instantiate(
                 _prefab ,
                 new Vector3( Random.Range(-8f,8f) , Random.Range(-5f,5f) ) ,
                 Quaternion.identity
             );
             transforms[i] = instance.transform;
             _velocities[i] = new float3{ y=Random.Range(1f,2f) };
         }
         _transformsAccess = new TransformAccessArray( transforms );
     }
 
     void OnDestroy ()
     {
         Dependency.Complete();
         if( _velocities.IsCreated ) _velocities.Dispose();
         if( _transformsAccess.isCreated ) _transformsAccess.Dispose();
     }
  
     void Update ()
     {
         Dependency.Complete();
 
         var job = new MyJob{
             deltaTime    = Time.deltaTime ,
             velocity    = _velocities
         };
         Dependency = job.Schedule( _transformsAccess );
     }

     [Unity.Burst.BurstCompile]
     public struct MyJob : IJobParallelForTransform
     {
         public NativeArray<float3> velocity;
         [ReadOnly] public float deltaTime;
         void IJobParallelForTransform.Execute ( int index , TransformAccess transform )
         {
             float3 vel = velocity[index];
             float3 pos = transform.position;
             {
                 pos += vel * deltaTime;
                 if( pos.y>5f ) vel = -math.abs(vel);
                 if( pos.y<-5f ) vel = math.abs(vel);
             }
             transform.position = pos;
             velocity[index] = vel;
         }
     }
 
 }

But wait, there's more!

The same behaviour, but converted to DOTS. 10k entities with Hybrid Renderer V2 enabled gave me 100-200 FPS :T

 using UnityEngine;
 
 using Unity.Entities;
 using Unity.Mathematics;
 using Unity.Transforms;
 
 using Random = UnityEngine.Random;
 
 public class SpawnZombiesFixedV2 : MonoBehaviour
 {
 
     [SerializeField] GameObject _prefab = null;
 
     void Start ()
     {
         var world = World.DefaultGameObjectInjectionWorld;
         var command = world.EntityManager;
 
         Entity entityPrefab;
         using( var blobAssetStore = new BlobAssetStore() )
         {
             var conversionSettings = GameObjectConversionSettings.FromWorld( world , blobAssetStore );
             entityPrefab = GameObjectConversionUtility.ConvertGameObjectHierarchy( _prefab , conversionSettings );
         }
         command.AddComponent<Velocity>( entityPrefab );
         
         for( int i=0 ; i<10000 ; i++ )
         {
             Entity instance = command.Instantiate( entityPrefab );
             command.SetComponentData( instance , new Translation{
                 Value = new float3{ x=Random.Range(-8f,8f) , y=Random.Range(-5f,5f) }
             } );
             command.SetComponentData( instance , new Velocity{
                 Value = new float3{ y=Random.Range(1f,2f) }
             } );
         }
     }
 
 }
 
 public class SpawnZombiesFixedV2System : SystemBase
 {
     protected override void OnUpdate ()
     {
         float deltaTime = Time.DeltaTime;
 
         Entities
             .WithName("update_positions_job")
             .ForEach( ( ref Translation position , in Velocity vel ) =>
             {
                 position.Value += vel.Value * deltaTime;
             } )
             .Schedule();
         
         Entities
             .WithName("update_velocity_job")
             .ForEach( ( ref Velocity vel , in Translation position ) =>
             {
                 if( position.Value.y>5f ) vel.Value = -math.abs(vel.Value);
                 if( position.Value.y<-5f ) vel.Value = math.abs(vel.Value);
             } )
             .Schedule();
     }
 }
 
 public struct Velocity : IComponentData
 {
     public float3 Value;
 }