Question You must call JobHandle.Complete() before you can write to the EntityCommandBuffer

Hi

i get this error lots of times and iam not sure why this happens:

Code (CSharp):

1. ArgumentException: The previously scheduled job ResetMapSystem:Update_LambdaJob0 writes to the Unity.Entities.EntityCommandBuffer Update_LambdaJob0.JobData.commandBuffer. You must call JobHandle.Complete() on the job ResetMapSystem:Update_LambdaJob0, before you can write to the Unity.Entities.EntityCommandBuffer safely.

Does this error happen because i have lots of systems which write to the same commandbuffer and DONT have a dependency on each other?

This is my code:

Code (CSharp):

1.  
2. protected sealed override void OnUpdate()
3. {
4.   var commandBuffer = _commandBufferSystem.CreateCommandBuffer();
5.   Update(commandBuffer);
6.   _commandBufferSystem.AddJobHandleForProducer(Dependency);
7. }
8.  

Code (CSharp):

1.  protected override void Update(EntityCommandBuffer commandBuffer)
2.     {
3.       Dependency = Entities.ForEach((Entity entity, ref Scale scale) =>
4.         {
5.           scale.Value = 1;
6.           commandBuffer.RemoveComponent<Visited>(entity);
7.         })
8.         .WithAll<Visited>()
9.         .Schedule(Dependency);
10.  
11.       commandBuffer.DestroyEntity(GetSingletonEntity<ResetMessage>());
12.     }

Thanks

 

You are scheduling a job that uses the ECB and then right after also writing to the ECB on the main thread. That is what it is complaining about.

 

aah this makes totally sense.

so the solution is to use the EntityManager to destroy the entity?

EDIT: no this doesnt work and results in the same error, but additionally in this:

Code (CSharp):

1. InvalidOperationException: The previously scheduled job ResetMapSystem:Update_LambdaJob0 reads from the Unity.Entities.EntityTypeHandle Update_LambdaJob0.JobData._lambdaParameterValueProviders.forParameter_entity._typeHandle. You must call JobHandle.Complete() on the job ResetMapSystem:Update_LambdaJob0, before you can deallocate the Unity.Entities.EntityTypeHandle safely.

 

You can create a second command buffer to destroy the entity.
or you can destroy entity first like this:

Code (CSharp):

1.  protected override void Update(EntityCommandBuffer commandBuffer)
2.     {
3.       commandBuffer.DestroyEntity(GetSingletonEntity<ResetMessage>());
4.       Dependency = Entities.ForEach((Entity entity, ref Scale scale) =>
5.         {
6.           scale.Value = 1;
7.           commandBuffer.RemoveComponent<Visited>(entity);
8.         })
9.         .WithAll<Visited>()
10.         .Schedule(Dependency);  
11.     }

when command is deferred, in most of the cases including your case, the order of the commands does not matter. Because your data processing job is done.

 

ah this works as expected thanks for the help

but why cant i just use the entitymanager here? i think iam missing a concept here

 

EntityManager's DestroyEntity will create a syncpoint right away. Invalidating all queries (including the one you use for the job). Command buffer defer the syncpoint to playback time.
It should still work if you use EntityManager.DestroyEntity first, before job schduale. But that's an undesierd syncpoint/structrual change. using command buffer is just better.

 

I have the same problem, but the script is a little different. What I am doing wrong?

Code (CSharp):

1. public partial class DeathCleanupSystem : SystemBase
2.     {
3.         private EndSimulationEntityCommandBufferSystem _ecbSystem;
4.  
5.         protected override void OnCreate()
6.         {
7.             _ecbSystem = World.GetOrCreateSystem<EndSimulationEntityCommandBufferSystem>();
8.         }
9.  
10.         protected override void OnUpdate()
11.         {
12.             Dependency.Complete();
13.  
14.             EntityCommandBuffer ecb = _ecbSystem.CreateCommandBuffer();
15.             Entities.WithBurst().WithAll<DeadData>().ForEach((Entity e) =>
16.             {
17.                 ecb.DestroyEntity(e);
18.             }).Schedule(Dependency);
19.            
20.             _ecbSystem.AddJobHandleForProducer(Dependency);
21.         }
22.        
23.     }

 

You're passing dependency to your job but not writing it back. Remove dependency from your schedule or write back to it from your job.

You don't need that complete.