Dynamic Gridmap unloading causes physics engine errors and FPS issues

[rumangerst]

Godot version: 3.1.1

OS/device including version: Ubuntu 19.10, AMD RX580, Mesa 19.2.1

Issue description:
Dynamically unloading GridMap tiles via set_cell_item(x,y,z,-1) (e.g. in a project that manages a large world) causes errors in the internal physics engine that are then shown in the editor error log. At the same time, unloading seems to not have the expected effect, as the FPS slows down noticeable the more world has been "covered" - even when the tiles actually have been removed.

Following errors are spammed in my error log (over 1000 errors in a short time; depending on how much unloading is done):

E 0:00:01:0791   Condition ' !id_map.has(p_rid.get_data()) ' is true. returned: __null
  <C Source>     ./core/rid.h:154 @ get()

E 0:00:01:0791   Condition ' !body ' is true.
  <C Source>     modules/bullet/bullet_physics_server.cpp:567 @ body_clear_shapes()

E 0:00:01:0791   Invalid ID
  <C Source>     modules/bullet/bullet_physics_server.cpp:1552 @ free()

Although the errors seem to be related to the physics server, they still come up if only mesh instances without physics or navigation are used as tiles.

Steps to reproduce:
Please see example project

Minimal reproduction project:
reproduce.zip

[pedronasser]

Its also happening in my project. Running on Windows (Godot v3.21.stable)
Any updates on this error?

[Calinou]

@pedronasser Does this occur if you change the physics engine to GodotPhysics instead of Bullet physics in the Project Settings? See #34963 and #28801.

[pedronasser]

@Calinou even changing it, it continues happening.
After some investigation I found out that it was because I was manually removing the cell item when based on distance, and it seems that when the PhysicsServer tries to remove if the mesh instance is outside of the screen then the errors starts happening.

[exe4que]

It happens to me also in my procedural world project. @pedronasser have you found any work around to it?

[rumangerst]

@exe4que I worked around it by creating multiple gridmaps, separating the world into chunks. Deleting a chunk works as expected.

[kzerot]

Have same bug, godot 3.2.3
Have no issues with FPS but also have these errors in console

[SoloCodeNet]

for an endless runner create and delete a lot of tiles with gridmap, adding a -1 value on a loop with non physic tile (no collisionShape instead) create lot of error debug and finally crash.
with an idle_frame the problem seem to be clear but it s a bad solution when removing lot of tiles.