Crash with user allocator

[Pierre-Terdiman]

Intro

Hello, I am interested in physics engines and starting to learn MuJoCo.

My setup

MuJoCo 3.2.2, C API, Windows

My question

According to the documentation (https://mujoco.readthedocs.io/en/stable/APIreference/APIglobals.html#mju-user-malloc), the user allocator must allocate memory aligned on 8-byte boundaries.

However if I do that, I get random crashes here and there.

It looks like it should be at least 64-byte aligned instead.

Could this be a doc bug ?

Minimal model and/or code that explain my question

No response

Confirmations

• I searched the latest documentation thoroughly before posting.
• I searched previous Issues and Discussions, I am certain this has not been raised before.

[oursland]

The AVX instructions are for 256-bit values max, which should be aligned along 32-byte boundaries. I suspect the documentation reflected an older version of the code that employed 64-bit SSE instructions.

[yuvaltassa]

Yup I think the OP is right that the documentation is wrong. However is think the correct aligment is to the size of the primitive type. doubles to 64, ints to 32, etc.

@saran-t please clarify.