Openpyxl does not close Excel workbook in read only mode

I've tried all these solutions for closing an xlsx file in read-only mode and none seem to do the job. I finally ended up using an in-mem file:

with open(xlsx_filename, "rb") as f:
    in_mem_file = io.BytesIO(f.read())

wb = load_workbook(in_mem_file, read_only=True)

Might even load faster and no need to worry about closing anything.

wb._archive.close()

Works with use_iterator too.

For your latest information, openpyxl 2.4.4+ provides Workbook.close() method. Below are references.

http://openpyxl.readthedocs.io/en/stable/changes.html?highlight=close#id86
https://bitbucket.org/openpyxl/openpyxl/issues/673

For some draconian reason, stackoverflow will allow me to post an answer but I don't have enough 'rep' to comment or vote -- so here we are.

The accepted answer of wb._archive.close() did not work for me. Possibly this is because I am using read-only mode. It may work fine when in 'normal' mode.

bmiller's answer is the only answer that worked for me as well:

with open(xlsx_filename, "rb") as f:
    in_mem_file = io.BytesIO(f.read())

wb = load_workbook(in_mem_file, read_only=True)

And as he said, it is faster when loading with open() versus only using read-only.

My working code based on bmiller's answer:

import openpyxl
import io

xlsx_filename=r'C:/location/of/file.xlsx'
with open(xlsx_filename, "rb") as f:
    in_mem_file = io.BytesIO(f.read())

wb = openpyxl.load_workbook(in_mem_file, read_only=True)