Bug Build on IOS crashing when multiple SetComputeBufferData are called in one frame

Hi,

I'm using Unity 2020.3.10f1 with an URP project.
I have a very simple code that can be used to repro this bug. Just attach the MonoBehaviour to an object in an empty scene and build for IOS.

Code (CSharp):

1. using System.Collections;
2. using System.Collections.Generic;
3. using UnityEngine;
4. using UnityEngine.Rendering;
5. using UnityEngine.UI;
6.  
7. public class TestCompute : MonoBehaviour
8. {
9.     private ComputeBuffer _gpuData1RB;
10.     private List<byte> _dat1 = new List<byte>();
11.     private int _frame = 0;
12.  
13.     private void Awake()
14.     {
15.         int dataSoupSize1 = 128 * 1024 * 1024;
16.  
17.         _gpuData1RB = new ComputeBuffer(dataSoupSize1, sizeof(int), ComputeBufferType.Raw);
18.         _frame = 0;
19.  
20.         for(int i = 0; i < 10 * 1024 * 1024; ++i)
21.         {
22.             _dat1.Add(0);
23.         }
24.     }
25.  
26.     private void OnDestroy()
27.     {
28.         if (_gpuData1RB != null)
29.         {
30.             _gpuData1RB.Release();
31.             _gpuData1RB = null;
32.         }
33.         RenderPipelineManager.beginFrameRendering -= BeginFrameRendering;
34.     }
35.  
36.     // Start is called before the first frame update
37.     void Start()
38.     {
39.         RenderPipelineManager.beginFrameRendering += BeginFrameRendering;
40.     }
41.  
42.     // Update is called once per frame
43.     void Update()
44.     {
45.     }
46.  
47.     void BeginFrameRendering(ScriptableRenderContext context, Camera[] cameras)
48.     {
49.         if(Application.isPlaying)
50.         {
51.             ComputeTest(context);
52.         }
53.     }
54.  
55.     void ComputeTest(ScriptableRenderContext context)
56.     {
57.         Debug.LogFormat("Ver 1 - frame {0}", ++_frame);
58.         CommandBuffer cmd;
59.  
60.         cmd = CommandBufferPool.Get();
61.  
62.         if((_frame % 3)  == 0)
63.         {
64.             cmd.SetComputeBufferData(_gpuData1RB, _dat1, 0, 0, 1 * 1024 * 1024);
65.             cmd.SetComputeBufferData(_gpuData1RB, _dat1, 0, 2 * 1024 * 1024, 1 * 1024 * 1024);
66.             cmd.SetComputeBufferData(_gpuData1RB, _dat1, 0, 3 * 1024 * 1024, 1 * 1024 * 1024);
67.         }
68.  
69.         context.ExecuteCommandBuffer(cmd);
70.         CommandBufferPool.Release(cmd);
71.     }
72. }
73.  

This code is running perfectly on PC and Android. On IOS it is crashing inside Unity:

CopyScratchArea[inlined] IsPrivate at MetalScratchBuffer.h:68

We did a test where we disabled the multithreaded rendering, but no luck:

As you can see it is crashing in the same place.

Any help with this will be appreciated.

Thank you!

 

Does anyone has an workaround the issue until (I hope), someone from Unity can fix the actual problem?

 

We face this bug too.

 

Hi @aleksandrk,
I'm not sure how to report it, so that's the reason I added everything with a simple example that can help re-create the issue.
By the way there is a problem also with the DX12 implementation. I have similar crashes with similar code.

Thank you