Exception AttributeError: AttributeError("'NoneType' object has no attribute 'error'",) in <bound method Connection.__del__ of <redis.connection.Connection object at 0x7fbe9e0a6190>> ignored

[xqliang]

Hi, I am using wsgi + apache2 to deploy my python web application. After i upgrade redis-py to 2.7.3, when i restart apache, apache alwarys show an error in apache_error_log: Exception AttributeError: AttributeError("'NoneType' object has no attribute 'error'",) in <bound method Connection.del of <redis.connection.Connection object at 0x7fbe9e0a6190>> ignored

My dev environment:
Python: 2.6.6
Redis-py: 2.7.3
Apache: Apache/2.2.16 (Debian)

I tried all redis-py<=2.7.2 are ok, and all redis-py>=2.7.3 could cause this problem.

[andymccurdy]

Do you have a stack trace or any other info? I suspect that this error has to do with this commit: a9a7623 however I'm not sure why.

I'm getting this same error...I am using the latest version of redis, python 2.7

[andymccurdy]

@kristen1980 do you have a stack trace by chance?

@andymccurdy Here's the most verbose logging I can get:

[Tue Apr 29 20:28:10 2014] [info] mod_wsgi (pid=507423): Daemon process inactivity timer expired, stopping process 'www.example.com'.
[Tue Apr 29 20:28:10 2014] [info] mod_wsgi (pid=507423): Shutdown requested 'www.example.com'.
[Tue Apr 29 20:28:10 2014] [info] mod_wsgi (pid=507423): Stopping process 'www.example.com'.
[Tue Apr 29 20:28:10 2014] [info] mod_wsgi (pid=507423): Destroying interpreters.
[Tue Apr 29 20:28:10 2014] [info] mod_wsgi (pid=507423): Destroy interpreter 'www.example.com|'.
[Tue Apr 29 20:28:10 2014] [info] mod_wsgi (pid=507423): Cleanup interpreter ''.
[Tue Apr 29 20:28:11 2014] [info] mod_wsgi (pid=507423): Terminating Python.
[Tue Apr 29 20:28:11 2014] [error] Exception AttributeError: AttributeError("'NoneType' object has no attribute 'error'",) in <bound method Connection.__del__ of Connection<host=localhost,port=13888,db=0>> ignored
[Tue Apr 29 20:28:11 2014] [error] Exception AttributeError: AttributeError("'NoneType' object has no attribute 'error'",) in <bound method Connection.__del__ of Connection<host=localhost,port=13888,db=0>> ignored
[Tue Apr 29 20:28:11 2014] [error] Exception AttributeError: AttributeError("'NoneType' object has no attribute 'error'",) in <bound method Connection.__del__ of Connection<host=localhost,port=13888,db=0>> ignored
[Tue Apr 29 20:28:11 2014] [info] mod_wsgi (pid=507423): Python has shutdown.
[Tue Apr 29 20:28:11 2014] [info] mod_wsgi (pid=515395): Attach interpreter ''.

That's the complete log and I'm not sure if the [info] stuff is relevant in this case but I include them because their timestamps are within at/near where the error occurs. Unlike the OP I don't get this everytime I restart apache...it just seems to magically occur in my error logs at times.

[andymccurdy]

@kristen1980 Thanks for the info. Does this actually have any negative side effects other than showing error messages in the apache log?

I looked at Connection.__del__. I'm surprised it's producing as this line (https://github.com/andymccurdy/redis-py/blob/master/redis/connection.py#L358) should be catching anything that Connection.disconnect might fail on.

What version of mod_wsgi are you running? I found this thread from on the django mailing list with similar errors showing up during Python termination. Graham, the author of mod_wsgi, suggests upgrading to mod_wsgi >= 3.3 because of some changes Python made in how to correctly exit() from C code.

Using mod_wsgi 3.4. No side effects to my knowledge. I mainly just wanted to make you and the other contributors aware.

[naoko]

I'm getting the same error.

Mon Apr 13 11:47:19.280639 2015] [:error] [pid 7301:tid 139860595107712] Exception AttributeError: AttributeError("'NoneType' object has no attribute 'error'",) in <bound method Connection.__del__ of Connection<host=localhost,port=6379,db=1>> ignored
[Mon Apr 13 11:47:19.280797 2015] [:error] [pid 7301:tid 139860595107712] Exception AttributeError: AttributeError("'NoneType' object has no attribute 'error'",) in <bound method Connection.__del__ of Connection<host=localhost,port=6379,db=1>> ignored
[Mon Apr 13 11:47:20.177511 2015] [mpm_event:notice] [pid 9420:tid 140441944024960] AH00489: Apache/2.4.7 (Ubuntu) mod_wsgi/3.4 Python/2.7.6 configured -- resuming normal operations

[cank]

I am running into this as well. Python's documentation has some interesting stuff regarding the del methods:

https://docs.python.org/3/reference/datamodel.html#object.__del__

I am still investigating, but some of these exceptions might just be being munged because objects are rebound to None.

Source for this all is here:

http://stackoverflow.com/questions/18163697/exception-typeerror-warning-sometimes-shown-sometimes-not-when-using-throw-meth

[pratikgs]

Also seeing the same error on Python 2.6, Redis 2.10.3
I suspect, it does slow down the apache response to the client ( even if there's no functional side-effect ) ? Any way we can mute this error ?

[dwoz]

Why call the disconnect method in del anyway? I think users of your library should be encouraged to call disconnect on their own. You could simply provide documentation explaining how to register an atexit method or some other standard cleanup method.

For others who just want to quiet this, in your codebase you can do this:

import redis.connection
def _redis_Connection_del(*args, **kwargs):
    return
redis.connection.Connection.__del__ = _redis_Connection_del

[erwinyusrizal]

Any update on this issue? I'm facing the same error using redis 2.10.6 and python 2.7

[eimsbush]

Same here using python3.8 and
django-redis==4.11.0
hiredis==1.0.1
redis==3.5.0

Exception ignored in: <function Connection.__del__ at 0x7fa5e8552040>
Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/redis/connection.py", line 537, in __del__
  File "/usr/local/lib/python3.8/site-packages/redis/connection.py", line 667, in disconnect
AttributeError: 'NoneType' object has no attribute 'error'

Edit: Just detected that always only this few lines were printed.

[andymccurdy]

This is a dupe of #1339. Closing this and continuing the discussion over there.