[SOLVED] How to Destroy World correctly?

Code (CSharp):

1. void Start()
2.     {
3.         _serWorld = new World("SerWorld");
4.         _serWorld.CreateManager<MoveJobSystem>();
5.         ScriptBehaviourUpdateOrder.UpdatePlayerLoop(_serWorld);
6.        
7.             //...
8.             //Create Entities
9.             //...
10.     }
11.  
12. public void Destroy()
13.     {
14.         _serWorld.Dispose();
15.         ScriptBehaviourUpdateOrder.UpdatePlayerLoop(World.Active);
16.     }

I got:
InvalidOperationException: Unity.Entities.SimulationSystemGroup has already been destroyed. It may not be used anymore.

 

This title wins a reward for best phrased question

 

It's a clickbait

 

Did you find the correct way ?

 

Still looking for an answer here, is it possible to have some feedback from the Unity team, please?

Here is what the error looks like if trying to dispose a world:

Code (CSharp):

1. NullReferenceException: Object reference not set to an instance of an object
2. Unity.Entities.ComponentSystemBase.AfterUpdateVersioning () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:317)
3. Unity.Entities.ComponentSystem.AfterOnUpdate () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:531)
4. Unity.Entities.ComponentSystem.InternalUpdate () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:578)
5. Unity.Entities.ComponentSystemBase.Update () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:166)
6. Unity.Entities.ComponentSystemGroup.OnUpdate () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystemGroup.cs:361)
7. UnityEngine.Debug:LogException(Exception)
8. Unity.Debug:LogException(Exception) (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/Stubs/Unity/Debug.cs:25)
9. Unity.Entities.ComponentSystemGroup:OnUpdate() (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystemGroup.cs:365)
10. Unity.Entities.ComponentSystem:InternalUpdate() (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:571)
11. Unity.Entities.ComponentSystemBase:Update() (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:166)
12. Unity.Entities.ComponentSystemGroup:OnUpdate() (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystemGroup.cs:361)
13. Unity.Entities.ComponentSystem:InternalUpdate() (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:571)
14. Unity.Entities.ComponentSystemBase:Update() (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:166)
15. Unity.Entities.DummyDelegateWrapper:TriggerUpdate() (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ScriptBehaviourUpdateOrder.cs:129)
16.  
17.  

which is followed by this error too:

Code (CSharp):

1. InvalidOperationException: Unity.Entities.PresentationSystemGroup has already been destroyed. It may not be used anymore.
2. Unity.Entities.ComponentSystemBase.CheckExists () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:208)
3. Unity.Entities.ComponentSystemBase.ShouldRunSystem () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:214)
4. Unity.Entities.ComponentSystem.InternalUpdate () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:554)
5. Unity.Entities.ComponentSystemBase.Update () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ComponentSystem.cs:166)
6. Unity.Entities.ScriptBehaviourUpdateOrder+DummyDelegateWrapper.TriggerUpdate () (at Library/PackageCache/com.unity.entities@0.0.12-preview.30/Unity.Entities/ScriptBehaviourUpdateOrder.cs:129)
7.  

 

I'm getting the same error too. Did you find a solution?

 

I make this thing. Works to me:

Code (CSharp):

1. _world.QuitUpdate = true;
2. ScriptBehaviourUpdateOrder.UpdatePlayerLoop(null);
3. // Or this:
4. // ScriptBehaviourUpdateOrder.SetPlayerLoop(PlayerLoop.GetDefaultPlayerLoop());
5. _world.EntityManager.CompleteAllJobs();
6. _world.EntityManager.DestroyAllEntity();
7. _world.Dispose();

But it's cheating. I don't remove world in fact.

 

i just tried to destroy a World with a simple :

Code (CSharp):

1. if (CachingWorld.IsCreated)
2.                 CachingWorld.Dispose();

and it works perfectly no errors.

 

It depends

 

Solution:

Code (CSharp):

1. _world = new World("name");
2. //... setup
3. _loopIndexes = _world.AddWorldToPlayerLoop();
4.  
5. //...
6.  
7. public async void Dispose()
8.         {
9.             _world.QuitUpdate = true;
10.             WorldExtensions.RemoveWorldFromPlayerLoop(_loopIndexes);
11.             _world.EntityManager.CompleteAllJobs();
12.            
13.             await Awaiters.NextFrame;
14.            
15.             _world.Dispose();
16.         }

Code (CSharp):

1. public static void RemoveWorldFromPlayerLoop(PlayerLoopTuple loopIndexes)
2.         {
3.             var resultPls = new PlayerLoopSystem {subSystemList = new PlayerLoopSystem[ScriptBehaviourUpdateOrder.CurrentPlayerLoop.subSystemList.Length]};
4.            
5.             for (var i = 0; i < ScriptBehaviourUpdateOrder.CurrentPlayerLoop.subSystemList.Length; i++)
6.             {
7.                 var sub = ScriptBehaviourUpdateOrder.CurrentPlayerLoop.subSystemList[i].subSystemList;
8.  
9.                 var resultSub = ScriptBehaviourUpdateOrder.CurrentPlayerLoop.subSystemList[i];
10.                 var tempSub = new PlayerLoopSystem[sub.Length];
11.  
12.                 var index = 0;
13.                 for (var j = 0; j < sub?.Length; j++)
14.                 {
15.                     if (sub[j].type == typeof(SimulationSystemGroup) && j == loopIndexes.SimulationIndex)
16.                     {
17.                         sub[j].updateDelegate = null;
18.                         sub[j] = new PlayerLoopSystem();
19.                         continue;
20.                     }
21.                     if (sub[j].type == typeof(PresentationSystemGroup) && j == loopIndexes.PresentationIndex)
22.                     {
23.                         sub[j].updateDelegate = null;
24.                         sub[j] = new PlayerLoopSystem();
25.                         continue;
26.                     }
27.                     if (sub[j].type == typeof(InitializationSystemGroup) && j == loopIndexes.InitializationIndex)
28.                     {
29.                         sub[j].updateDelegate = null;
30.                         sub[j] = new PlayerLoopSystem();
31.                         continue;
32.                     }
33.  
34.                     tempSub[index] = sub[j];
35.                     index++;
36.                 }
37.                
38.                 Array.Resize(ref tempSub, index);
39.                 resultSub.subSystemList = tempSub;
40.                    
41.                 resultPls.subSystemList[i] = resultSub;
42.             }
43.  
44.             ScriptBehaviourUpdateOrder.SetPlayerLoop(resultPls);
45.         }
46.        
47.         public static PlayerLoopTuple AddWorldToPlayerLoop(this World world)
48.         {
49.             var result = PlayerLoopTuple.CreateEmpty;
50.            
51.             if (ScriptBehaviourUpdateOrder.CurrentPlayerLoop.subSystemList == null)
52.             {
53.                 ScriptBehaviourUpdateOrder.UpdatePlayerLoop(world);
54.                 for (var i = 0; i < ScriptBehaviourUpdateOrder.CurrentPlayerLoop.subSystemList.Length; i++)
55.                 {
56.                     var sub = ScriptBehaviourUpdateOrder.CurrentPlayerLoop.subSystemList[i].subSystemList;
57.                     for (var j = 0; j < sub?.Length; j++)
58.                     {
59.                         if (sub[j].type == typeof(SimulationSystemGroup))
60.                         {
61.                             result.SimulationIndex = j;
62.                         }
63.                         else if (sub[j].type == typeof(PresentationSystemGroup))
64.                         {
65.                             result.PresentationIndex = j;
66.                         }
67.                         else if (sub[j].type == typeof(InitializationSystemGroup))
68.                         {
69.                             result.InitializationIndex = j;
70.                         }
71.                     }
72.                 }
73.                 return result;
74.             }
75.  
76.             // Take the previous systems that were running.
77.             var a = ScriptBehaviourUpdateOrder.CurrentPlayerLoop;
78.  
79.             // Create a player loop from the given world.
80.             ScriptBehaviourUpdateOrder.UpdatePlayerLoop(world);
81.             var b = ScriptBehaviourUpdateOrder.CurrentPlayerLoop;
82.  
83.             var resultPls = new PlayerLoopSystem {subSystemList = new PlayerLoopSystem[a.subSystemList.Length]};
84.            
85.            
86.             for (var i = 0; i < a.subSystemList.Length; i++)
87.             {
88.                 var aSub = a.subSystemList[i].subSystemList;
89.                 var bSub = b.subSystemList[i].subSystemList;
90.  
91.                 var resultSub = a.subSystemList[i];
92.                 resultSub.subSystemList = new PlayerLoopSystem[aSub.Length + 1];
93.  
94.                 for (var j = 0; j < aSub.Length; j++)
95.                 {
96.                     resultSub.subSystemList[j] = aSub[j];
97.                 }
98.  
99.                 for (var j = 0; j < bSub?.Length; j++)
100.                 {
101.                     // Only add the systems that are specific to the world.
102.                     // Don't add other systems, they are internal to Unity (e.g. like WaitForTargetFPS).
103.  
104.                     if (bSub[j].type == typeof(SimulationSystemGroup))
105.                     {
106.                         result.SimulationIndex = aSub.Length;
107.                         resultSub.subSystemList[aSub.Length] = bSub[j];
108.                     }
109.                     else if (bSub[j].type == typeof(PresentationSystemGroup))
110.                     {
111.                         result.PresentationIndex = aSub.Length;
112.                         resultSub.subSystemList[aSub.Length] = bSub[j];
113.                     }
114.                     else if (bSub[j].type == typeof(InitializationSystemGroup))
115.                     {
116.                         result.InitializationIndex = aSub.Length;
117.                         resultSub.subSystemList[aSub.Length] = bSub[j];
118.                     }
119.                 }
120.  
121.                 resultPls.subSystemList[i] = resultSub;
122.             }
123.  
124.             ScriptBehaviourUpdateOrder.SetPlayerLoop(resultPls);
125.             return result;
126.         }