[Pymilter] no memory release when assigning chunks to self.fp in milter-template.py

[joao reis]

Hi,

milter-template.py seems to accumulate memory constantly while saving 
the message chunks in self.fp.

Here is a minor adaptation of the milter-template running on python3 (I 
noticed the same problem with pymilter running on python2) follows 
(https://github.com/joaoreis81/milter-template) with few modifications 
that reproduce the problem. On a reasonably loaded postfix server, after 
30 minutes of messaging the process memory increased to 500MB

In my last tests, I am running milter-template as a container and the 
increase in memory occurs both when running directly in the operating 
system and the container environment. We can certainly exclude this as a 
possible cause of the problem described.

As stated earlier, all file descriptors cleanup tests were done but 
unsuccessful for memory release, it looks like a "memory cancer" really.

I have been using Red Hat based operating systems (fedora, centos) and 
the problem always comes up. I will perform some tests changing 
distribution to verify the result.

I am passing this thread to the mailing list as directed.


Thanks in advance
João Reis.