JobTempAlloc has allocations that are more than 4 frames old

Unity Engine
,
1

Hello,

I have a job that copies the positions of the tanks and another job that consumes them to check the distance, for this I use a NativeArray but it shows me the following warning and I don’t understand the reason.

Internal: JobTempAlloc has allocations that are more than 4 frames old - this is not allowed and likely a leak

using Components.Tags;
using Unity.Burst;
using Unity.Collections;
using Unity.Entities;
using Unity.Jobs;
using Unity.Mathematics;
using Unity.Transforms;

namespace Systems
{
    [UpdateInGroup(typeof(SimulationSystemGroup))]
    public class BulletVsTankCollisionSystem : JobComponentSystem
    {
        private EntityQuery _tankGroup;
        private EntityQuery _bulletGroup;
       
        private BeginInitializationEntityCommandBufferSystem _commandBufferSystem;
       
        protected override void OnCreate()
        {
            _tankGroup = GetEntityQuery(new EntityQueryDesc
            {
                All = new[] {ComponentType.ReadOnly<Tank>(), ComponentType.ReadOnly<Translation>()},
            });
           
            _bulletGroup = GetEntityQuery(new EntityQueryDesc
            {
                All = new[] {ComponentType.ReadOnly<Bullet>(), ComponentType.ReadOnly<Translation>()},
            });
           
            _commandBufferSystem = World.GetOrCreateSystem<BeginInitializationEntityCommandBufferSystem>();
        }

        [BurstCompile]
        private struct CopyPositions : IJobForEachWithEntity<Translation>
        {
            public NativeArray<float3> Positions;
            public NativeArray<Entity> Entities;

            public void Execute(Entity entity, int index, [ReadOnly] ref Translation localToWorld)
            {
                Positions[index] = localToWorld.Value;
                Entities[index] = entity;
            }
        }

        [BurstCompile]
        [RequireComponentTag(typeof(Bullet))]
        private struct CheckDistanceJob : IJobForEachWithEntity<Translation>
        {
            [DeallocateOnJobCompletion] [ReadOnly] public NativeArray<float3> CopyTankPositions;
            [DeallocateOnJobCompletion] [ReadOnly] public NativeArray<Entity> CopyTankEntities;
            [ReadOnly] public EntityCommandBuffer CommandBuffer;

            public void Execute(
                Entity entity,
                int index,
                [ReadOnly] ref Translation translation
            )
            {
                // TODO: Check distance, add damage...
                CommandBuffer.DestroyEntity(entity);
            }
        }

        protected override JobHandle OnUpdate(JobHandle inputDeps)
        {
            var tankCount = _tankGroup.CalculateLength();
            var copyTankPositions = new NativeArray<float3>(tankCount, Allocator.TempJob,
                NativeArrayOptions.UninitializedMemory);
            var copyTankEntities = new NativeArray<Entity>(tankCount, Allocator.TempJob,
                NativeArrayOptions.UninitializedMemory);

            var copyTankPositionsJob = new CopyPositions
            {
                Positions = copyTankPositions,
                Entities = copyTankEntities
            };
            var copyTankPositionsJobHandle = copyTankPositionsJob.Schedule(_tankGroup, inputDeps);

            var checkDistanceJob = new CheckDistanceJob
            {
                CopyTankPositions = copyTankPositions,
                CopyTankEntities = copyTankEntities,
                CommandBuffer = _commandBufferSystem.CreateCommandBuffer()
            };
           
            var checkDistanceJobHandle = checkDistanceJob.Schedule(_bulletGroup, copyTankPositionsJobHandle);

            _commandBufferSystem.AddJobHandleForProducer(checkDistanceJobHandle);
         
            return checkDistanceJobHandle;
        }
    }
}

How can I solve that? Is there a better way to do it?

Thanks in advance.

2

Is it maybe that your deallocations are in the CheckDistanceJob but if there’s no bullets, that job is not going to run?
I don’t know what ecs does behind the scenes if the _bulletGroup is empty and whether it’ll still DeallocateOnJobCompletion even if the job doesn’t run.

Maybe first check if _bulletGroup.CalculateLength() == 0 and if so just exit OnUpdate. Presumably there’s no point running the tankPositions job and allocating arrays if there’s no bullets?
Otherwise you can try tack on a third job that runs regardless to deallocate the arrays, or create the arrays as instance members of BulletVsTankCollisionSystem and dispose them at the start of OnUpdate each frame.

3

You could also try using RequireForUpdate protected method on your 2 EQ on OnCreate so that it must either run until the deallocation or not update at all.

4

Ah I knew I forgot one. :slight_smile:
Yes RequireForUpdate in OnCreate is best option.

protected override void OnCreate() {
    ...
    RequireForUpdate(_tankGroup);
    RequireForUpdate(_bulletGroup);
}
1 Like
5

Both one and the other work, I will use RequireForUpdate :smile:

Thank you very much.

1 Like
6

I got this all the time, and before banging your head looking for bugs, restart Unity.
Usually they are leaking, not me.

6 Likes
7

I’m really glad to have read and tried this. Seems that leaving Unity open and going suspension mode it’s “not supported” by Unity itself.

8

Is this correct?