SIGKILL on some models using Ubuntu on Github Actions

Summary:

It seems like for some posteriors, running stan for just two iterations without warmup end up in a SIGKILL on Github actions using Ubuntu.

Description:

For two different models of posteriordb (fims_Aus_Jpn_irt-2pl_latent_reg_irt and at-hier_2pl), I currently get error code 137 on Github Actions.

Reproducible Steps:

The whole GitHub action run with all systems information can be found here:
https://github.com/stan-dev/posteriordb/actions/runs/1220973431
and here:
https://github.com/stan-dev/posteriordb/actions/runs/1220529384

The run with at-hier_2pl I have rerun on Github Action multiple times with the exact same result (exit code 137).

I have run both these models locally on my mac without any problems.

Let me know if I can do something to help to debug.

Start with the linked GitHub Actions runs and reproduce the two named posteriordb models, fims_Aus_Jpn_irt-2pl_latent_reg_irt and at-hier_2pl, on Ubuntu with two iterations and no warmup. Compare the run information with the successful local macOS executions; done means identifying and resolving the repeated exit code 137 without breaking these model runs.