Add optional unwind dependency to py-spy to enable native tracing

[HackToHell]

Since benfred/py-spy#768 unwind became optional, unfortunately without this, native=True flag doesn't really work.

The commit is synced into grafana/py-spy as well.

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[korniltsev]

The unwind feature has been disabled and removed from pyroscope-rs to "reduce maintenance surface".

[korniltsev]

grafana/py-spy@20ecc5b

[HackToHell]

@korniltsev What would be the recommended alternative? Should I use the alloy ebpf tracer

[korniltsev]

Can you share what is your use case? What type of app do you have to profile? How do stack traces look if obtained from py-spy?

You may try alloy's pyroscope.ebpf profiler or opentelemetry-ebpf-profiler and see if it satisfies your needs

[HackToHell]

Can you share what is your use case? What type of app do you have to profile? How do stack traces look if obtained from py-spy?

I am running it on ML pipelines, they have a dataloader written in CPP which is loaded with pybind11. I tried using pyroscope.ebpf with alloy main, but it dooesn't seem to load native traces either ( I suspect, it detects python process and discards anything else).

Sample from a version with native switched on with py bind - A demo I used for testing

[korniltsev]

Yes, this is perfectly valid use case. We need either bring back libunwind ( :( ) or have native unwinding in rust.

[korniltsev]

@HackToHell would you like to continue work on this and revert my changes that removed libunwind? Or would you prefer me to do this?
I think removing libunwind was a mistake. And short term we should return it. Long term we better have rust written native unwinder, but that will take forever to implement