poplib 100% cpu usage

Oli Schacher python at lists.wgwh.ch
Wed Jul 16 17:01:08 CEST 2008


Hi all

I wrote a multithreaded script that  polls mails from several pop/imap 
accounts. To fetch the messages I'm using the getmail classes ( 
http://pyropus.ca/software/getmail/ ) , those classes use the poplib for 
the real pop transaction.

When I run my script for a few hours cpu usage goes up to 100%, 
sometimes even 104% according to 'top' :-) This made our test machine 
freeze once. First I thought I maybe didn't stop my threads correctly 
after polling an account but I attached a remote debugger and it showed 
that threads are stopped ok and that the cpu gets eaten in poplib in the 
function "_getline" which states in the description:

---snip---
  # Internal: return one line from the server, stripping CRLF.
     # This is where all the CPU time of this module is consumed.
     # Raise error_proto('-ERR EOF') if the connection is closed.

     def _getline(self):
---snip---


So for testing purposes I changed this function and added:
time.sleep(0.0001)
(googling about similar problems with cpu usage yields this time.sleep() 
trick)

It now looks ok, cpu usage is at about 30% with a few spikes to 80-90%.

Of course I don't feel cozy about changing a standard library as the 
changes will be overwritten by python upgrades.

Did someone else from the list hit a similar problem and maybe has a 
better solution?


Thanks for your hints.

Best regards,
Oli Schacher



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