Investigate musllinux-arm64 CI test hangs for Python 3.9, 3.10, 3.11

[korniltsev-grafanista]

Description

In the linux-test CI matrix added in grafana/pyroscope-rs#364, the musllinux-arm64 variant hangs indefinitely for Python 3.9, 3.10, and 3.11, while 3.12 and 3.13 complete successfully (~37s each).

All four variants started at the same time. The three older versions never complete.

Observed behaviour

Job	Status	Duration
musllinux-arm64 - 3.9	stuck in_progress	15+ min
musllinux-arm64 - 3.10	stuck in_progress	15+ min
musllinux-arm64 - 3.11	stuck in_progress	15+ min
musllinux-arm64 - 3.12	completed	~37s
musllinux-arm64 - 3.13	completed	~37s

Example run: https://github.com/grafana/pyroscope-rs/actions/runs/22293868489

Possible causes

• python:3.9-alpine, python:3.10-alpine, python:3.11-alpine images may not have an arm64 variant on Docker Hub, causing docker pull to hang or fail silently
• py-spy may not support profiling on Alpine arm64 for older Python versions
• The test watchdog (120s timeout) fires but the process doesn't exit cleanly inside the container

Current workaround

These three combinations are excluded from the matrix via exclude: in ci-ffi-python.yml until the root cause is identified.

Next steps

• Check Docker Hub for python:3.9-alpine / 3.10-alpine / 3.11-alpine arm64 manifest availability
• Run the docker pull manually on an arm64 runner to confirm
• Check if py-spy works on Alpine arm64 for these Python versions