Bug Burst compile error and IJobEntity dependency troubleshooting

Hey everyone,

I am working with ECS for quite a while now, so I am definitely not a beginner. Just yesterday I ran into a baffling burst compile error, that I just can't seem to track down, so I was hoping I can get some help here.

The error message I am getting:

Code (CSharp):

1. (0,0): Burst error BC1091: External and internal calls are not allowed inside static constructors: Interop.BCrypt.BCryptGenRandom(System.IntPtr hAlgorithm, byte* pbBuffer, int cbBuffer, int dwFlags)
2.  
3. While compiling job:
4. Unity.Entities.JobEntityBatchIndexExtensions+JobEntityBatchIndexProducer`1[[Tellas.Storylets.ECS.Systems.FindAvailablePersonsJob, Tellas.Storylets, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]], Unity.Entities, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null::Execute(Unity.Entities.JobEntityBatchIndexExtensions+JobEntityBatchIndexWrapper`1[[Tellas.Storylets.ECS.Systems.FindAvailablePersonsJob, Tellas.Storylets, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]]&, Unity.Entities, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null|System.IntPtr, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089|System.IntPtr, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089|Unity.Jobs.LowLevel.Unsafe.JobRanges&, UnityEngine.CoreModule, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null|System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
5. Unity.Entities.JobEntityBatchIndexExtensions+JobEntityBatchIndexProducer`1[[Tellas.Storylets.ECS.Systems.RemoveDuplicatesJob, Tellas.Storylets, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]], Unity.Entities, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null::Execute(Unity.Entities.JobEntityBatchIndexExtensions+JobEntityBatchIndexWrapper`1[[Tellas.Storylets.ECS.Systems.RemoveDuplicatesJob, Tellas.Storylets, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null]]&, Unity.Entities, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null|System.IntPtr, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089|System.IntPtr, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089|Unity.Jobs.LowLevel.Unsafe.JobRanges&, UnityEngine.CoreModule, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null|System.Int32, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089)
6.  

The system in which the error is supposedly happening:

Code (CSharp):

1. using Tellas.Character.ECS.Components;
2. using Tellas.Core.ECS;
3. using Tellas.PhysicsEngine.ECS.Components;
4. using Tellas.Storylets.ECS.Components;
5. using Unity.Burst;
6. using Unity.Collections;
7. using Unity.Entities;
8. using Unity.Transforms;
9.  
10. namespace Tellas.Storylets.ECS.Systems
11. {
12.  
13.     [UpdateInGroup(typeof(TellasLateSimulationSystemGroup))]
14.     public partial class FindAvailablePersonsSystem : SystemBase
15.     {
16.         EndSimulationEntityCommandBufferSystem commandBufferSystem;
17.  
18.         protected override void OnCreate()
19.         {
20.             commandBufferSystem = World.GetExistingSystem<EndSimulationEntityCommandBufferSystem>();
21.         }
22.  
23.         protected override void OnUpdate()
24.         {
25.             EntityCommandBuffer ecb = commandBufferSystem.CreateCommandBuffer();
26.  
27. //Can be parallelized
28.             Entities
29.                .WithName("RemoveAvailablePersonTag")
30.                .WithAll<Tag_AvailablePerson>()
31.                .WithStructuralChanges()
32.                .ForEach((Entity e) =>
33.                 {
34.                     //
35.                     EntityManager.RemoveComponent<Tag_AvailablePerson>(e);
36.                 }).Run();
37.  
38. //not sure how to parallelize - remove and recreate efficient enough?
39.             Entities
40.                .WithName("ClearAvailableToTalk")
41.                .WithAll<AvailableToTalk>()
42.                .WithAll<AvailableToTalk>()
43.                .WithStructuralChanges()
44.                .ForEach((Entity e) =>
45.                 {
46.                     //
47.                     EntityManager.GetBuffer<AvailableToTalk>(e).Clear();
48.                 }).Run();
49.  
50.             Dependency = new FindAvailablePersonsJob
51.                 {
52.                     canTalks = GetComponentDataFromEntity<CanTalk>()
53.                   , persons = GetComponentDataFromEntity<Person>()
54.                   , availablePersons = GetComponentDataFromEntity<Tag_AvailablePerson>()
55.                   , ecb = ecb.AsParallelWriter()
56.                 }.ScheduleParallel(Dependency);
57.  
58.             Dependency = new RemoveDuplicatesJob
59.                 {
60.                     ecb = ecb.AsParallelWriter()
61.                 }.ScheduleParallel(Dependency);
62.  
63.             commandBufferSystem.AddJobHandleForProducer(Dependency);
64.         }
65.     }
66.  
67.     [BurstCompile]
68.     [WithAll(typeof(Tag_FindAvailablePersons))]
69.     [WithAll(typeof(Tag_PhysicsTrigger))]
70.     [WithAll(typeof(CollisionTriggerResult))]
71.     public partial struct FindAvailablePersonsJob : IJobEntity
72.     {
73.         [ReadOnly] public ComponentDataFromEntity<CanTalk> canTalks;
74.         [ReadOnly] public ComponentDataFromEntity<Person> persons;
75.         [ReadOnly] public ComponentDataFromEntity<Tag_AvailablePerson> availablePersons;
76.  
77.         public EntityCommandBuffer.ParallelWriter ecb;
78.  
79.         public void Execute(Entity e, [EntityInQueryIndex] int entityInQueryIndex, in Parent parent, in DynamicBuffer<CollisionTriggerResult> collisionResults)
80.         {
81.             Entity parentEntity = parent.Value;
82.  
83.             for(int i = 0; i < collisionResults.Length; ++i)
84.             {
85.                 CollisionTriggerResult triggerResult = collisionResults[i];
86.  
87.                 Entity other = triggerResult.a == e ? triggerResult.b : triggerResult.a;
88.                 if(!canTalks.HasComponent(other) || !persons.HasComponent(other))
89.                     continue;
90.  
91.                 if(!availablePersons.HasComponent(other))
92.                     ecb.AddComponent<Tag_AvailablePerson>(entityInQueryIndex, other);
93.  
94.                 AvailableToTalk element = new(other, persons[other]);
95.  
96.                 ecb.AppendToBuffer(entityInQueryIndex, parentEntity, element);
97.             }
98.         }
99.     }
100.  
101.     [BurstCompile]
102.     [WithAll(typeof(AvailableToTalk))]
103.     public partial struct RemoveDuplicatesJob : IJobEntity
104.     {
105.         public EntityCommandBuffer.ParallelWriter ecb;
106.  
107.         public void Execute(Entity e, [EntityInQueryIndex] int entityInQueryIndex, ref DynamicBuffer<AvailableToTalk> buffer)
108.         {
109.             ecb.RemoveComponent<AvailableToTalk>(entityInQueryIndex, e);
110.             DynamicBuffer<AvailableToTalk> newBuffer = ecb.AddBuffer<AvailableToTalk>(entityInQueryIndex, e);
111.  
112.             NativeParallelHashSet<AvailableToTalk> set = new(buffer.Length, Allocator.Temp);
113.             for(int i = 0; i < buffer.Length; ++i)
114.             {
115.                 set.Add(buffer[i]);
116.             }
117.  
118.             int j = 0;
119.             newBuffer.Length = set.Count();
120.             foreach(AvailableToTalk availableToTalk in set)
121.             {
122.                 newBuffer[j++] = availableToTalk;
123.             }
124.  
125.             set.Dispose();
126.         }
127.     }
128.  
129. }
130.  

The only constructors being called are on the `AvailableToTalk` dynamic buffer element and the hashset for duplicate removal (if there is a faster way, please let me know!)

AvailableToTalk looks like this:

Code (CSharp):

1. [InternalBufferCapacity(8)]
2.     public struct AvailableToTalk : IBufferElementData, IEquatable<AvailableToTalk>
3.     {
4.         // Actual value each buffer element will store.
5.         public Entity value;
6.         public Person person;
7.  
8.         public AvailableToTalk(Entity value, Person person)
9.         {
10.             this.value = value;
11.             this.person = person;
12.         }
13.  
14.         public bool Equals(AvailableToTalk other)
15.         {
16.             return value.Equals(other.value) && person.Equals(other.person);
17.         }
18.  
19.         public override bool Equals(object obj)
20.         {
21.             return obj is AvailableToTalk other && Equals(other);
22.         }
23.  
24.         public override int GetHashCode()
25.         {
26.             return HashCode.Combine(value, person);
27.         }
28.  
29.         public static bool operator ==(AvailableToTalk left, AvailableToTalk right)
30.         {
31.             return left.Equals(right);
32.         }
33.  
34.         public static bool operator !=(AvailableToTalk left, AvailableToTalk right)
35.         {
36.             return !left.Equals(right);
37.         }
38.     }

And Person is simply an IComponentData with a single int for an ID, nothing more.

I really don't understand where the error is coming from. I assume it is in the codegen from IJobEntity, but even there I don't see anything specific.

Before I moved the code to an IJobEntity from a Entities.ForEach it was working fine without errors, but it was also running without burst originally, so no clue if the problem was already occuring before or not.

Any help is greatly appreciated!
Loofou

 

It’s probably the HashCode.Combine call in AvailableToTalk.GetHashCode (the hash set should rely on GetHashCode to function). The .NET HashCode struct as implemented by the BCL Unity uses probably does some magic stuff in its static constructor (considering that the current version on dotnet/runtime main does so), so you’d want to derive your own hashing for that struct, or just use an IDE function to make one.

 

Hm right, let me try to combine manually via prime multiplication.

Edit:

Yeah that one should've been obvious. Damn you code-completion automation

Thanks for the hint on that, the error is gone. Unfortunately I get another error now, but I hope I can figure this one out myself.

Code (CSharp):

1. The system Tellas.Storylets.ECS.Systems.FindAvailablePersonsSystem reads Tellas.PhysicsEngine.ECS.Components.CollisionTriggerResult via FindAvailablePersonsJob but that type was not assigned to the Dependency property. To ensure correct behavior of other systems, the job or a dependency must be assigned to the Dependency property before returning from the OnUpdate method.

It's a bit weird because I am adding both jobs to the Dependency field...

 

Yeah I can't figure this one out either. All jobs are added to the Dependency field, I even removed the main-thread entities.foreach temporarily and it still complains. The only way to get it to stop is to not use ECBs at all and run everything on the main thread, but I refuse to go down that route unless there is really no other option.

Usually when this error occured I did some weird stuff with jobhandle combines that it could not detect properly, but in this case everything is super straight forward so I really don't get it :/

After writing 50 systems without any big issues, this one is really getting on my nerves

 

Right, thanks for confirming. And yes, a callstack would've been extremely helpful
Replacing the HashCode.Combine with a manual hashing worked. I think I will replace the auto-creation template from Rider with a more burst-friendly approach.

Right now I ran into a follow-up error (see my last message), which I also never had like this before. I'm sure there is a similar simple solution, but from my knowledge I can't figure it out.

 

Haha, no problem at all much appreciated!

 

Thanks for the answer! How can I make a local edit to this file without Unity redownloading the package every time I try to save?

Edit:
Nevermind, found it. (here, for anyone else looking: https://www.reddit.com/r/Unity3D/comments/hmbm46/can_i_edit_a_unity_package/)

This does indeed change the error to

Code (CSharp):

1. [ERR] [UNITY] "InvalidOperationException: The previously scheduled job FindAvailablePersonsJob writes to the Unity.Entities.EntityCommandBuffer FindAvailablePersonsJob.JobData.ecb. You must call JobHandle.Complete() on the job FindAvailablePersonsJob, before you can write to the Unity.Entities.EntityCommandBuffer safely."

So does that means I need one command buffer per job? I never knew that, always just reused the same one, but it makes sense. I hope the order is still dependent on the Dependency handle if I use two ecbs. I will try this.

Edit2:

I think I got it. My second job is reading the buffer I'm writing in the job before, but I'm not actually waiting for the ecb to be finished. I should probably find a better way to remove duplicates from my buffer

Thanks everyone for the help! Much appreciated!

 

Your issue is

ecb.AsParallelWriter

In first job you call it and pass to job, and schedule, after that point any read\write access of ecb (safety checks inside

AsParallelWriter

check if someone write to ecb) - not allowed by safety system. What you should do in that case (if jobs depends on each other) is - declare

ecbParallel

right before first job and assign

ecb.AsParallelWriter()

, and just pass

ecbParallel

to both of your jobs.