blob.py: ResourceWarning unclosed file

[zopyx]

Plone 5.2, Python 3.6.

We perform a migration import over plone.restapi.

Each uploaded file results in warning on the console

/home/ajung/sandboxes/ugent-portaal-plone-4x/eggs/ZODB-5.5.1-py3.6.egg/ZODB/blob.py:339: ResourceWarning: unclosed file <_io.FileIO name='/tmp/BUCe14dcpak' mode='rb' closefd=True>
super(BlobFile, self).close()

[d-maurer]

"zopefoundation/transaction#82" is potentially related.

[zopyx]

The issue is still pending (any annoying)...I still see the error in Plone 6.0.0a4:

/Users/ajung/src/plone6.buildout/eggs/ZODB-5.7.0-py3.9.egg/ZODB/blob.py:338: ResourceWarning: unclosed file <_io.FileIO name='/Users/ajung/src/plone6.buildout/var/blobstorage/0x00/0x00/0x00/0x00/0x01/0x88/0xa1/0xa6/0x03e8a997b8fa1233.blob' mode='rb' closefd=True>

[d-maurer]

The issue is still pending (any annoying)...I still see the error in Plone 6.0.0a4:

/Users/ajung/src/plone6.buildout/eggs/ZODB-5.7.0-py3.9.egg/ZODB/blob.py:338: ResourceWarning: unclosed file <_io.FileIO name='/Users/ajung/src/plone6.buildout/var/blobstorage/0x00/0x00/0x00/0x00/0x01/0x88/0xa1/0xa6/0x03e8a997b8fa1233.blob' mode='rb' closefd=True>

Potentially, this is not a ZODB problem: I have recently hunted down ResourceWarnings in the context of ZEO. Many ZEO tests involve blobs and none of them has raised a blob related ResourceWarning.

I assume that application code forgets to call close on a BlobFile.

[zopyx]

At least in my case, there is no add-on code involved that would deal with blobs directly.

[dataflake]

In your situation I would manually add debugging code to see where in the code the warning is originating and what that blob item is. That may help.

[d-maurer]

It is quite easy to determine the context which has created an improperly finalized resource:
export PYTHONTRACEMALLOC=frcount; then rerun. This remembers frame information for up to frcount frames with each allocated object; a RessourceWarning will include the remembered information for the respective resource.