The gzip docs for Python 3 states that

Calling a GzipFile object’s close() method does not close fileobj, since you might wish to append more material after the compressed data

Does this mean that the gzip file handler f_in is not closed if we do the following

import gzip
import shutil
with gzip.open('/home/joe/file.txt.gz', 'rb') as f_in:with open('/home/joe/file.txt', 'wb') as f_out:shutil.copyfileobj(f_in, f_out)

If so, will this cause a leak if this code is executed multiple times?

The warning about fileobj not being closed only applies when you open the file, and pass it to the GzipFile via the fileobj= parameter. When you pass only a filename, GzipFile "owns" the file handle and will also close it.