IndexOutOfRangeException error for code that used to work

Unity Engine
,
1

I’m having trouble with this code that used to work

Debug.Log($"{tileIndexStartLocal.Length} {testIndex}");
var c = tileIndexStartLocal[testIndex];
Debug.Log("test");

First output is “288 4” and I never get the “test” outputted in the console.

I get this error:

IndexOutOfRangeException: Index 4 is out of restricted IJobParallelFor range [0…3] in ReadWriteBuffer.
ReadWriteBuffers are restricted to only read & write the element at the job index. You can use double buffering strategies to avoid race conditions due to reading & writing in parallel to the same elements from a job.

this happens inside an Entities.ForEach, tileIndexStartLocal is a persistent NativeArray that is set up in Update function before the Entities.ForEach. In the ForEach I only read from this array.

Anyone got any clues what’s up?

Thanks!

2

Please post whole related part of the job.
It feels something else is going on there.

Are you testing this single threaded, or multithreaded?

3

Thanks for the reply, it’s a huge job, as it’s my own custom physics system.

I’ll try creating a new system to reproduces the bug and post it here!

4

Here we go, this code isn’t pretty but I removed everything else, but what’s needed to get the error:

public void FixedUpdate()
{
    var stepCount = 10;
    
    TileIndexStart = new NativeArray<int>(288, Allocator.Persistent);

    JobHandle[] stepJob1Handle = new JobHandle[stepCount];
    JobHandle[] stepJob2Handle = new JobHandle[stepCount];

    for (int step = 0; step < stepCount; step++)
    {
        if (step == 0)
        {
            stepJob1Handle[step] = Dependency;
        }
        else
        {
            stepJob1Handle[step] = stepJob2Handle[step - 1];
        }
        
        var tileIndexStartLocal = TileIndexStart;

        stepJob2Handle[step] = Entities.ForEach((ref Physics p) =>
        {
            var testIndex = 4;
            Debug.Log($"{tileIndexStartLocal.Length} {testIndex}"); // 288 4
            var c = tileIndexStartLocal[testIndex]; // <- stops here
            Debug.Log("test");
        }).ScheduleParallel(stepJob1Handle[step]);
    }
    
    Dependency = stepJob2Handle[stepCount - 1];
    Dependency.Complete();
}
        }
5

You’re missing .WithReadOnly(tileIndexStartLocal)

2 Likes
6

Yay!! That’s it, now it works! Thanks a million! I wasn’t aware of WithReadOnly and this worked before with a previous version of the Entities package.