feat: skip Python runtime objects in callgrind

[not-matthias]

No description provided.

[codspeed-hq]

Merging this PR will not alter performance

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

⚡ 21 improved benchmarks
❌ 24 (👁 24) regressed benchmarks
✅ 232 untouched benchmarks

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
⚡	WallTime	test_recursive_fibo_20	5.5 ms	5.4 ms	+2.43%
⚡	WallTime	test_combination_sum[candidates0-8]	12 µs	11.4 µs	+5.25%
👁	WallTime	test_multiprocessing_map[1000]	58.8 ms	60.7 ms	-3.12%
👁	WallTime	test_color[graph0-3]	30.1 µs	31.4 µs	-4%
👁	WallTime	test_open_close_fd[100]	882.8 µs	919.1 µs	-3.94%
⚡	WallTime	test_fs_write[1000]	18.7 µs	18 µs	+4.15%
👁	WallTime	test_tcp_connection[1.1.1.1-53]	1.1 ms	1.1 ms	-4.32%
⚡	WallTime	test_n_queens_solve[board0]	11.1 ms	10.9 ms	+2.29%
👁	WallTime	test_open_knight_tour[1]	4.3 µs	4.4 µs	-2.26%
👁	WallTime	test_noop_lambda_decorated	1.3 µs	1.3 µs	-2.59%
👁	WallTime	test_multiprocessing_map[10000]	89.9 ms	108.8 ms	-17.36%
⚡	WallTime	test_match_word_pattern[aba-GraphTreesGraph]	109.7 µs	106.6 µs	+2.92%
⚡	WallTime	test_hamilton_cycle[graph0]	26.1 µs	25.4 µs	+2.82%
👁	WallTime	test_generate_all_combinations[5-4]	10.1 µs	10.6 µs	-5%
⚡	WallTime	test_sum_of_squares[sum_of_squares_sum_comprehension_product]	198.5 µs	192.9 µs	+2.93%
⚡	WallTime	test_fs_write[10000]	44.6 µs	41.8 µs	+6.62%
👁	WallTime	test_tcp_connection[google.com-443]	1.2 ms	1.2 ms	-3.64%
⚡	WallTime	test_fs_read[1000]	878.4 ns	850.2 ns	+3.31%
⚡	WallTime	test_hostname_resolution[google.com]	397.4 µs	388.6 µs	+2.26%
👁	WallTime	test_process_creation[cat /dev/null]	5.3 ms	5.4 ms	-2%
...	...	...	...	...	...

ℹ️ Only the first 20 benchmarks are displayed. Go to the app to view all benchmarks.

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_{Comparing cod-2654-flamegraph-doesnt-work-on-valgrind (3bbabe4) with master (d4d9dc6)}

[Copilot]

Pull request overview

Adds a Callgrind/Valgrind client-request hook so CodSpeed can instruct Callgrind to ignore Python runtime object files (libpython + the python executable), reducing noise in Callgrind-derived flamegraphs.

Changes:

• Add a new C-extension method callgrind_add_obj_skip(bytes_path) that issues a custom Valgrind client request.
• Add Python helpers to resolve and register object-file paths (including realpath) for skipping.
• Invoke the skip logic during InstrumentHooks initialization to hide Python runtime frames by default.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
src/pytest_codspeed/instruments/hooks/instrument_hooks_module.c	Exposes a new C-extension entrypoint that emits a Callgrind client request to skip an object file by path.
src/pytest_codspeed/instruments/hooks/__init__.py	Adds Python wrappers to call the extension and automatically skip libpython + the Python executable in Callgrind.

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[GuillaumeLagrange]

OLGTM, trusting you on how we retrieve the skipped path from python runtime

[GuillaumeLagrange]

lgtm, discussed the callgrind.h and let's keep it this way temporarily