Re: Why POE is slower then Python - Twisted ... quite a lot?

It is too soon to conclude that POE is the cause.

The difference in CPU time between your Python and Perl tests is  
0.0002 seconds per article (user+sys).  It's not a significant  
difference at this scale.  It could be caused by any number of low- 
level variations between POE and Twisted, or Perl and Python.

The wall times are a better place to look for inefficiencies.  They  
are three orders of magnitude larger than the total CPU times.

The large difference between wall and CPU times indicates a non-CPU  
bottleneck.  In your test case, it's probably the network.

What could account for network differences?

You are comparing two different NNTP client libraries.  They may  
interact differently with the server, which is a likely place to  
look.  To investigate this, I would scale the tests down to a small  
number of articles (2 < count <= 10).  I would dump the resulting  
network traffic for each test.  I would use the dumps to compare  
interaction patterns between the two libraries.  I would also look at  
timings: the times between command & response, the times between one  
command and the next, the length of time to receive an article, and so  
on.  tcpdump and tshark (or wireshark) are very good for this sort of  
thing.

If network interaction is comparable, we should revisit the points I  
outlined in my last message.  They don't seem to have made much of an  
impression, but they may still be relevant.

Thank you.

-- 
Rocco Caputo - [email protected]

On Mar 25, 2009, at 13:18, howard chen wrote:

> But anyway, now I re-run the test, instead of downloading 100 posts,
> now I download 1K articles.
>
>>> python
> real    3m6.007s
> user    0m0.088s
> sys     0m0.016s
>
>>> perl
> real    6m13.730s
> user    0m0.268s
> sys     0m0.024s