Standard library xml.ElementTree - iterparse does not close filehandle properly when breaking out of a for loop iterating with iterparse. The issue only occurs when the user passes a "string" as a source object instead of a filehandle (that is because a user's filehandle can safely be closed in a context manager as shown in the attachment).

which version of Python were you doing this on?

The function in question is https://github.com/python/cpython/blob/master/Lib/xml/etree/ElementTree.py#L1233-L1278

ran python 3.9.2 on windows 10

1) What did you do?
Tried to remove folder that contains a xml file that was worked on by ElementTree iterparse with argument source='filename' (string type input)
2. What happened?
python was not able to remove the folder due to file lock still held by iterparse.
3. What did you expect to happen
iterparse was supposed to close the filehandle such that the user could then write/move/delete the xml file worked on, however python gave a PermissionError:

Traceback (most recent call last):
  File "C:\Users\vkisf\Desktop\00_MYSTUFF\01_SOFTWARE\01_PYTHON\01_GITHUB\pycascades2021\ETiterparse.py", line 43, in <module>
    shutil.rmtree('subdir2')
  File "C:\Users\vkisf\Desktop\00_MYSTUFF\01_SOFTWARE\01_PYTHON\01_GITHUB\pycascades2021\cpython\lib\shutil.py", line 740, in rmtree
    return _rmtree_unsafe(path, onerror)
  File "C:\Users\vkisf\Desktop\00_MYSTUFF\01_SOFTWARE\01_PYTHON\01_GITHUB\pycascades2021\cpython\lib\shutil.py", line 618, in _rmtree_unsafe
    onerror(os.unlink, fullname, sys.exc_info())
  File "C:\Users\vkisf\Desktop\00_MYSTUFF\01_SOFTWARE\01_PYTHON\01_GITHUB\pycascades2021\cpython\lib\shutil.py", line 616, in _rmtree_unsafe
    os.unlink(fullname)
PermissionError: [WinError 32] The process cannot access the file because it is being used by another process: 'subdir2\\app.xml'

Example script attached works perfectly on macOS 

> python3.9 test.py
[('default', 'http://schemas.openxmlformats.org/officeDocument/2006/extended-properties'), ('vt', 'http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes')]
[('default', 'http://schemas.openxmlformats.org/officeDocument/2006/extended-properties'), ('vt', 'http://schemas.openxmlformats.org/officeDocument/2006/docPropsVTypes')]

Confirmed that no apps were using the created xml file or folder. Windows Explorer was closed for all folders only the terminal shell was open. Issue still persists on windows 10 OS.

"erase all files"

Perhaps this can be handled with Issue 25707, which is open for adding an API to close the file, similar to how "os.scandir" iterator implements a context manager and "close" method.

New changeset 496c428de3318c9c5770937491b71dc3d3f18a6a by Jacob Walls in branch 'main':
bpo-43292: Fix file leak in `ET.iterparse()` when not exhausted (GH-31696)
https://github.com/python/cpython/commit/496c428de3318c9c5770937491b71dc3d3f18a6a

New changeset 8acbb93c0763fa53b5959fe05d86ba275c9e8a5b by Miss Islington (bot) in branch '3.10':
bpo-43292: Fix file leak in `ET.iterparse()` when not exhausted (GH-31696)
https://github.com/python/cpython/commit/8acbb93c0763fa53b5959fe05d86ba275c9e8a5b

New changeset 852d9b77abefcad2bb8d203e3ab9f2ca49ab305f by Miss Islington (bot) in branch '3.9':
[3.9] bpo-43292: Fix file leak in `ET.iterparse()` when not exhausted (GH-31696) (GH-31720)
https://github.com/python/cpython/commit/852d9b77abefcad2bb8d203e3ab9f2ca49ab305f