Originally reported byBuck Evan (Bitbucket: bukzor, GitHub: bukzor)
The hypothesis library recently added coverage-led fuzzing, in which it needs to run a very short test many times, while examining the coverage between each trial. This (currently) involves many calls to coverage.Collector.save_data, which in turn causes many calls to realpath (and thus lstat). In the extreme case, lstat() ends up taking about 40% of the run time.
Can you please help me design a remedy? Some alternatives that I can think of:
add a cache to files.abs_file
replace the call to abs_file with a call to files.canonical_path, since canonical_path already has a cache
Delegate the filename-normalization responsibility from Collector to CoverageData, such that we can specialize CoverageData and fix this within our dependent library.