Intermittent Invalid file object error

[msornay]

Hello,

I am not certain that it is an aiopg issue, but we are sometime encountering the following error :

File "/usr/local/lib/python3.5/dist-packages/aiopg/cursor.py", line 113, in execute
    yield from self._conn._poll(waiter, timeout)
File "/usr/local/lib/python3.5/dist-packages/aiopg/connection.py", line 193, in _poll
    self._ready(self._weakref)
File "/usr/local/lib/python3.5/dist-packages/aiopg/connection.py", line 162, in _ready
    self._loop.add_writer(self._fileno, self._ready, weak_self)
File "/usr/lib/python3.5/asyncio/selector_events.py", line 272, in add_writer
    key = self._selector.get_key(fd)
File "/usr/lib/python3.5/selectors.py", line 189, in get_key
    return mapping[fileobj]
File "/usr/lib/python3.5/selectors.py", line 70, in __getitem__
    fd = self._selector._fileobj_lookup(fileobj)
File "/usr/lib/python3.5/selectors.py", line 224, in _fileobj_lookup
    return _fileobj_to_fd(fileobj)
File "/usr/lib/python3.5/selectors.py", line 39, in _fileobj_to_fd
    "{!r}".format(fileobj)) from None
ValueError: Invalid file object: None

It happens rarely, during the execution of the UPDATE step of a transaction with the following queries :

1. BEGIN ;
2. SELECT column FROM table WHERE condition FOR UPDATE ;
3. UPDATE table SET column = value WHERE condition ;
4. COMMIT ; (Which is never executed when the error occurs, never releasing the SELECT FOR UPDATE lock)

Environment :

• PostgreSQL 9.5.3
• Ubuntu 16.04 (dockerized)
• Python 3.5.2
• aiopg 0.11

[asvetlov]

Looks like you have flaky network connection.
The only case when self._fileno becomes None is https://github.com/aio-libs/aiopg/blob/master/aiopg/connection.py#L146
This line is called only if postgres client was silently disconnected from server.

Sure, the error message should be more informative, I'll fix it.

[msornay]

I just noticed there probably were more case where that happened in 0.11
Thank you, I will update.

[asvetlov]

Fixed by 1ce153c