CKAN Version if known (or site URL)

2.5.2

Please describe the expected behaviour

When file resource saved to FileStore, datapusher is notified about it, downloads the resource, process the file, create new table in DataStore and sets datastore_active flag for the particular resource.

Please describe the actual behaviour

It's working as described, though when uploading multiple resources (eg. through API), there is a race condition probably in ckan.lib.dictization.model_save.package_dict_save (or somewhere in the stack trace).
Sometimes the problem can even produce "Resource not found" in logs though it's most certainly there at the time. That's a case where datapusher tries to patch the resource and set datastore_active to True.

What steps can be taken to reproduce the issue?

In httpd conf file, the race condition can be "resolved" with forcing one process and one thread for CKAN.
Something like this in ckan httpd config file:
WSGIDaemonProcess ckan display-name=ckan processes=1 threads=1
If it's eg. 15 threads and 2 processes, the described issue appears.