Reading from a 2 dimensional array in multiple threads results in values that are not in the array

[D0V4HKIIN]

Tested versions

• Reproducible in: 4.3.stable

System information

Godot v4.3.stable (77dcf97d8) - Gentoo 2.15 - Wayland - Vulkan (Forward+) - integrated AMD Radeon Graphics (RADV RENOIR) - AMD Ryzen 5 5600U with Radeon Graphics (12 Threads)

Issue description

When reading a 2 dimensional array with multiple threads, some values read are not values that are in the original array.

Steps to reproduce

1. Create 2 dimensional of at least size 2 (i.e. [[], []])
2. Create multiple threads
3. Print values in 2d array
4. Notice values being printed that are not in the original array.

Minimal reproduction project (MRP)

MRP.zip

[AThousandShips]

You are looping forever, and it won't print anything in my testing, when fixing the code by removing the infinite loop, then it just prints nothing as intended

When looping a single time or a fixed number of times nothing is printed and everything works as expected

[D0V4HKIIN]

Hmm I am not getting this behavior at all. I will come back with a screen recording when I have time.

[AThousandShips]

Haven't tested in 4.3 but the MRP you provided doesn't do what you are describing, did you actually test with the MRP?

[D0V4HKIIN]

Here is the output that I am getting. Also the output changes from time to time (guess depending on what is in memory).

https://github.com/user-attachments/assets/17e17848-c66b-4e0f-8ad6-be5ae39cbf03

[AThousandShips]

Please show your errors, and please try without the infinite loop

[D0V4HKIIN]

Ran the MRP again

Output

Errors: 388 times the same error (and once it complaining about icon.svg missing)

Debugger:

[D0V4HKIIN]

Without the infinite loop it doesn't complain and doesn't print anything.

The goal of the infinite loop is to trigger what I believe is some race condition.