GH-115060: Speed up pathlib.Path.glob() by skipping directory scanning - #116152
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barneygale wants to merge 6 commits into
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GH-115060: Speed up pathlib.Path.glob() by skipping directory scanning#116152barneygale wants to merge 6 commits into
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… scanning. For ordinary literal pattern segments (e.g. `foo/bar` in `foo/bar/../**`), skip calling `_scandir()` on each segment, and instead call `exists()` or `is_dir()` as necessary to exclude missing paths. This only applies when *case_sensitive* is `None` (the default); otherwise we can't guarantee case sensitivity or realness with this approach. If *follow_symlinks* is `False` we also need to exclude symlinks from intermediate segments. This restores an optimization that was removed in da1980a by some eejit. It's actually even faster because we don't `stat()` intermediate directories, and in some cases we can skip all filesystem access when expanding a literal part (e.g. when it's followed by a non-recursive wildcard segment).
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Quite a lot faster: $ ./python -m timeit -s "from pathlib import Path" "list(Path().glob('Lib/pathlib/__init__.py'))"
2000 loops, best of 5: 195 usec per loop # before
20000 loops, best of 5: 17 usec per loop # after
$ ./python -m timeit -s "from pathlib import Path" "list(Path().glob('Lib/pathlib/*'))"
2000 loops, best of 5: 197 usec per loop # before
10000 loops, best of 5: 28.8 usec per loop # after
$ ./python -m timeit -s "from pathlib import Path" "list(Path().glob('Lib/*/__init__.py'))"
200 loops, best of 5: 1.24 msec per loop # before
1000 loops, best of 5: 307 usec per loop # after
$ ./python -m timeit -s "from pathlib import Path" "list(Path().glob('*/pathlib/__init__.py'))"
200 loops, best of 5: 1.22 msec per loop # before
1000 loops, best of 5: 261 usec per loop # after
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For ordinary literal pattern segments (e.g. foo/bar in foo/bar/../**), skip calling scandir() on each segment, and instead call exists() or is_dir() as necessary to exclude missing paths. This only applies when case_sensitive is None (the default); otherwise we can't guarantee case sensitivity or realness with this approach. If follow_symlinks is False we also need to exclude symlinks from intermediate segments.
This restores an optimization that was removed in da1980a by some eejit. It's actually even faster because we don't stat() intermediate directories, and in some cases we can skip all filesystem access when expanding a literal part (e.g. when it's followed by a non-recursive wildcard segment).