entity-command-buffer

To make structural changes from within a Unity DOTS parallel job, record operations like AddComponent or DestroyEntity using an EntityCommandBuffer. This queues the changes so they can be safely replayed on the main thread after the job finishes, preventing invalid entity states.

An EntityCommandBuffer in Unity DOTS is used to record structural entity operations such as Instantiate and RemoveComponent during job execution. It defers these changes so they can be safely applied at a specific frame boundary, preserving deterministic behavior and preventing runtime errors.

To ensure deterministic playback across parallel workers, use the EntityCommandBuffer.ParallelWriter and provide a stable sort key, such as the chunk index. This guarantees a predictable and stable replay order when the deferred structural changes are finally applied.

Destroying entities directly inside an IJobEntity causes runtime errors because structural changes invalidate active entity iteration and chunk data. You must defer the destruction by recording it to an EntityCommandBuffer, which safely applies the changes after the job completes.

Yes, you can use an EntityCommandBuffer with Burst-compiled jobs in Unity DOTS. You need to obtain the ECB from an EntityCommandBufferSystem singleton and use its AsParallelWriter method to safely record structural changes from within the Burst job.

You should play back structural changes recorded in an EntityCommandBuffer at the correct frame boundary using the appropriate EntityCommandBufferSystem, such as BeginSimulationEntityCommandBufferSystem. This ensures changes are applied safely on the main thread after simulation timing.