direct-entity-manager-structural-changes

Safe EntityManager structural changes in Unity DOTS require performing one-shot batch operations on the main thread outside of SystemAPI.Query foreach loops and scheduled jobs. Use batch overloads and query-based Add, Remove, or Destroy APIs to ensure correctness and avoid archetype fragmentation.

Direct EntityManager batch operations are appropriate for one-shot initialization, infrequent config-driven respawns, and mass batch structural changes on the main thread. Avoid using this approach for per-frame hot paths to prevent expensive archetype operations and performance degradation.

Accessing EntityManager inside SystemAPI.Query causes issues because iterating active queries while making structural changes invalidates entity references and corrupts archetype chunks. Safety patterns dictate using batch overloads and query-based APIs outside the foreach loop to maintain data integrity.

Yes, you can mass Instantiate prefabs on the main thread using state.EntityManager.Instantiate(prefab, count, Allocator.Temp). Disable the one-shot ISystem with state.Enabled = false before executing work, then apply component or buffer changes via batch or query-based APIs.

Limitations include the inability to access EntityManager from scheduled jobs and the prohibition against making structural changes inside SystemAPI.Query foreach loops. Using direct EntityManager operations on per-frame hot paths causes expensive archetype operations and should be avoided for regular updates.

Direct EntityManager structural changes do not work with scheduled burst jobs. Accessing EntityManager from jobs breaks safety patterns; structural changes must be executed as one-shot batch operations on the main thread using query-based Add, Remove, and Destroy overloads.