Fix memory leak#8
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_get_range_string was wrapped in functools.lru_cache(maxsize=None) and is called once per cell with the cell's coordinates as the key, so the cache grew by one permanent entry for every cell of every workbook written in the process. Measured in a long-running test suite: 3.57M entries (~1GB+) after writing one large report set, at a 14% hit rate -- the cache barely functioned while growing monotonically. The string formatting it avoided is cheaper than the cache machinery, and the genuinely cacheable part (_get_column_letter) keeps its own cache, whose key space (column numbers) is naturally tiny. Co-Authored-By: Claude Fable 5 <[email protected]>
openpyxl's is already cached (unbounded, unfortunately).
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_get_range_string was wrapped in
functools.lru_cache(maxsize=None)and is called once per cell with the cell's coordinates as the key, so the cache grew by one permanent entry for every cell of every workbook written in the process. Measured in a long-running test suite: 3.57M entries (~1GB+) after writing one large report set, at a 14% hit rate.The string formatting it avoided is cheap, and the call to
get_column_letteris already cached by openpyxl.