[Pymilter] milter multiprocess (or multithread)

[Marco]

Hello Stuart,

On 10/12/2019 02:51, Stuart D. Gathman wrote:
> On Mon, 9 Dec 2019, Marco wrote:
> 
>> All works fine as expected. But with *threads* only, it seems that the 

> You should verify that runmilter returns on SIGTERM by adding another
> print immediately after Milter.runmilter().

yes, I verified this. Even with a "print" just after the runmilter, no 
output has been printed out after SIGTERM:

# ../venv/bin/python3 milter-template.py
2019Dec10 08:33:05 milter startup
Terminated
#

The code:
   [...]
   Milter.runmilter("myfilter",socketname,timeout)
   print("%s Just after runmilter: bms milter shutdown" % 
time.strftime('%Y%b%d %H:%M:%S'))
   logq.put(None)
   bt.join()
   print("%s bms milter shutdown" % time.strftime('%Y%b%d %H:%M:%S'))
   [...]


>> If I well understand this is a limitation from libmilter interface. I 
>> don't understand how to avoid this limit really. For instance, could I 
>> terminate the milter sending a "stop" command?
> 
> I discuss this in https://pymilter.org/pymilter/index.html in "threading".
> I'll be happy to add any addition info you uncover on user threads
> with libmilter.  :-)
> 
> The libmilter docs discussion is here:
> https://pymilter.org/pymilter/milter_api/overview.html#SignalHandling

Interesting. You say "Threads may still be useful, but you may need to 
provide an alternate means of causing graceful shutdown.
You may find the multiprocessing module useful."
Ok, this is the only solution that I found to obtain a graceful 
shutdown. So I suppose there is no way to have a graceful shutdown with 
threading in pymilter.
There is not a Milter.Milter stop(self) function to print something when 
SIGTERM or other signal happens, and then stop :(

Thank you for the clarification.

Anyway pymilter is the best for me. I'm surprised about the power of 
this package! Thank you to share this.

Marco