Re: [cclib-devel] progress support

[Noel O'B. <no...@ca...>]

On Thu, 2006-03-09 at 12:03 -0800, Adam Tenderholt wrote:
> So I added an example progress class called TextProgress which basically 
> prints out bars saying how much progress has been made, and made necessary 
> changes to G03 parser to allow use of this class.
> 
> If you want to use it, first create an instance, and pass that instance to the 
> G03 class along with the filename:
> 
> progress=TextProgress()
> p=G03(filename,progress)
> p.parse()

Got it. Works fine, although doesn't play well with the logger, but you
can turn the logger off or get it to write to a file.

> I changed the __init__ function of G03 to accept any amount of arguments, and 
> pass that onto the baseclass. See the SVN diffs for more details. This allows 
> the user of cclib to not specify a parser and continue as before.
Yes, and seems to be just as fast if you don't specify a progress.

> Unfortunately, not all of this message is good news. Calling G03 with a 
> TextParser adds a 20-25% overhead: 4 seconds becomes 5ish, 21 seconds becomes 
> more like 26, etc. I think the problem is that it calls the 
> progress.update(step) far too frequently.
I don't know where the slow step is. I've added a call to random so that
it only calls it every so many steps, but there isn't a massive
improvement.

>  It may make more sense to identify 
> the slower parts of the parsing class, and only add progress.update there, 
> but I don't know for sure.
> 
> Any ideas on how to improve this?
Not really. I think this is the price you pay. A bit like Heisenberg's
uncertainty principle - by observing the progress you change it. :-) If
we could identify more clearly the slow step - for example, is it the
call to tell()? - then we could think about how to improve it. I tried
various things to speed up the textprogress, but they only made a minor
difference.

BTW, you may be interested in:
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/299207
http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/168639

Regards,
 Noel