Filter out "comments" in inferno-flamegraph input

[Mike Roberts]

The austin Python profiler includes some metadata as "comments" in its output, e.g.:

# austin: 3.3.0
# interval: 100
# mode: wall
# python: 3.9.10

P247;T247;<frozen importlib._bootstrap>:_install_external_importers:1187;<frozen importlib._bootstrap>:_find_and_load:1007;<frozen importlib._bootstrap>:_find_and_load_unlocked:986;<frozen importlib._bootstrap>:_load_unlocked:680;<frozen importlib._bootstrap>:exec_module:838;<frozen importlib._bootstrap_external>:<module>:35;<frozen importlib._bootstrap>:_find_and_load:1007;<frozen importlib._bootstrap>:_find_and_load_unlocked:986;<frozen importlib._bootstrap>:_load_unlocked:680;<frozen importlib._bootstrap>:exec_module:768;<frozen importlib._bootstrap>:_call_with_frames_removed:228 53
...
P247;T247;/home/mike/profiling/test.py:<module>:6;/usr/lib/python3.9/dis.py:dis:79;/usr/lib/python3.9/dis.py:_disassemble_recursive:373;/usr/lib/python3.9/dis.py:disassemble:369;/usr/lib/python3.9/dis.py:_disassemble_bytes:404 180

# duration: 695345
# sampling: 6,15,159
# saturation: 10/3898
# errors: 4/3898

Most of these are correctly ignored as invalid lines by inferno-flamegraph, but some (like # duration: 695345) look enough like a valid sample to end up in the output svg. I think the original perl version correctly identifies all of them as invalid, since it uses a strict regex to parse lines.

It's fairly trivial to work around this with a sed '/^#/d', but it would be nice for austin and inferno-flamegraph to work together smoothly.

Would you accept a PR to filter out all lines which begin with # in inferno-flamegraph?

Thanks

[Jon Gjengset]

Absolutely — that seems reasonable!