CommandBuffer.AppendToBuffer<>() doesn't execute before the next job call

Unity Engine
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1

I noticed while using CommandBuffer.AppendToBuffer<>() there’s a chance that the buffer wasn’t appended before the next call to the job. This causes my code to create unpredictable segments. Is this intended or am i supposed to do something else to make sure the IBufferElement is added before the next call to the job?

2

There’s not really enough information here to help you. If you’re scheduling your jobs the normal way this shouldn’t be possible. You’d need to show the code.

3

I have a normal IJob and initialize it with this.

var MoveSpawnJobBHandle = new MoveSpawnJobB
                    {
                        BufferHandle = GetBufferFromEntity<EntitySectionBuffer3V>(true),
                        collisionWorld = collisionWorld,
                        commandBuffer = commandBuffer,
                        PhysicsVelocityGroup = GetComponentDataFromEntity<PhysicsVelocity>(true),
                        MoveIdentifierGroup = GetComponentDataFromEntity<MoveIdentifier>(true),
                        MovesToSpawn = MovesToSpawn, // <- premade native list
                        TranslationGroup = GetComponentDataFromEntity<Translation>(true),
                        entities = MoveQuery.ToEntityArray(Allocator.TempJob),
                        debug = true,
                        verbose = true,
                        spawnLimit = 2
                    }.Schedule(Dependency);
                    MoveSpawnJobBHandle.Complete();
                    m_EndSimulationEntityCommandBufferSystem.AddJobHandleForProducer(MoveSpawnJobBHandle);

the job loops through the entities and appends to the buffer using an EntityCommandBuffer. i use the CommandBuffer grabbed from the EndSimulationEntityCommandBufferSystem system.

The job creates an entity and a joint that joins the newly created entity to the entity at the end of the buffer. the result is a rope-like object connected by joints. The code works fine (I’ve tested it on the main thread using EntityManager instead of EnittyCommandBuffer).

here’s the code i use to append the buffer

commandBuffer.AppendToBuffer( entities[i], new EntitySectionBuffer3V
                                                    {
                                                        EntityA = data.sender, //entity grabbed from the native list MovesToSpawn
                                                        EntityB = CurrentStringShotEntity, // entity crated using the command buffer
                                                        value = data.spawnType, // int value
                                                        EntityC = joint // joint entity created using the command buffer
                                                    });
4

I did some more tests and it really does seem that the 2 jobs are executing on the same frame causing them to grab the same data and act according causing a duplicate.

6678319--765274--upload_2021-1-1_17-13-3.png

I made the code name the entity StringShotBodyX where X is the length of the buffer when the job executes so something is definitely fishy.

for now i’ll try using commandBuffer.Playback(EntityManager) and see if there’s a difference

5

Just tested using commandBuffer.Playback(EntityManager) and it seems to work fine.