Archivematica

For all the details, see GitHub issue https://github.com/artefactual/archivematica/issues/708.

To re-create: using AM qa/1.x and SS qa/0.x, create an AIP and then attempt to do a metadata-only reingest on it. AM should spin its wheels for 5 seconds and then notify you that "Error re-ingesting package: An unknown error occurred." If you insert some logging lines before and after https://github.com/artefactual/archivematica-storage-service/blob/qa/0.x/storage_service/locations/models/package.py#L843, you will see that the log messages after that line do not get called: the call to bag.validate(processes=4) hangs indefinitely. If you replace that call with the original bag.validate() everything works as normal.

Cause: Thanks to Jesús for figuring out the source of this: it's an incompatibility between Gunicorn's gevent worker class and BagIt's use of multiprocessing. In order for bag.validate(processes=4) to work, Gunicorn must be using the sync worker class.