Advantanges - You cannot trace a Python process line by line in py-spy. Because py-spy does not attach the line's probe. By the way, py-spy is a profiler, beetrace is a tracer. - You can see the call/return hierarchy of a Python process because beetrace attaches function entry and function return probes.

Disadvantages - To trace the process, Python must be configured with the --with-dtrace option. Otherwise, you won't be able to trace it.