id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
28500	"""EOFError: Ran out of input"" from Django file cache when file is empty"	Justin Crown	caleb logan	"When using Django file cache, if a cache file ends up empty for some reason (yes, this actually happened in the wild), an `EOFError` is thrown.

Steps to reproduce:

Cache must be set to `django.core.cache.backends.filebased.FileBasedCache`.

{{{
>>> from django.core.cache import cache
>>> cache.set('testing' 'test')
}}}

In a shell

{{{
> cache_dir/file_that_got_created.djcache
}}}

Back in the REPL

{{{
>>> cache.get('testing')
Traceback (most recent call last):
  File ""/usr/local/lib/python3.6/code.py"", line 91, in runcode
    exec(code, self.locals)
  File ""<console>"", line 1, in <module>
  File ""/usr/local/lib/python3.6/site-packages/django/core/cache/backends/filebased.py"", line 40, in get
    if not self._is_expired(f):
  File ""/usr/local/lib/python3.6/site-packages/django/core/cache/backends/filebased.py"", line 137, in _is_expired
    exp = pickle.load(f)
EOFError: Ran out of input
}}}

As to how these files would end up empty to begin with, I would hazard to guess that it is caused by a rare race condition in the file moving process:

https://github.com/django/django/blob/master/django/core/files/move.py#L59

Whereby if this process is interrupted by a system shutdown, the file is created in the appropriate location but is empty.

Desired behavior would be that in this situation, an exception would not be thrown. Rather, `None` (or default) would be returned.

I am planning on working on a patch towards this, but wanted to log the ticket first."	Bug	closed	Core (Cache system)	1.11	Normal	fixed			Accepted	0	0	0	0	0	0