[Tutor] performance considerations

Andrei Kulakov ak@silmarill.org
Mon, 03 Dec 2001 13:37:50 -0500


On Mon, Dec 03, 2001 at 01:31:13PM -0500, dman wrote:
> On Mon, Dec 03, 2001 at 01:10:41PM -0500, Andrei Kulakov wrote:
> | On Mon, Dec 03, 2001 at 12:51:39PM -0500, dman wrote:
> | > 
> | > I'm working on a script/program to do some processing (munging) on
> | > text files in a directory tree.  In addition, for convenience, all
> | > non-interesting files are copied without munging.  My script, as it
> | > stands, is quite CPU intensive so I would like to optimize it some.
> | > 
> | > In the case of copying non-interesting files, what is (generally) the
> | > most efficient way?  It seems there is no system-level "copy" command.
> | 
> | shutil.copy()
> 
> Cool, thanks.
> 
> | > A portion of the script generates strings by starting with 'a' and
> | > "adding" to it.  Ie "a", "b", ..., "z", "aa", "ab", ..., "zz", "aaa".
> | > Would it be better to use a list of one-char-strings than to modify a
> | > single string?  Here's the code I have now (BTW, that funny-looking
> 
> I forgot to mention, if a list of strings is used, each yield will
> yield  "".join( the_list ), so the comparison is the multiple
> modifications (creation) of strings versus join.

Yeah, that's what I thought.. I think I remember someone saying that one
join would be much faster.

> 
> | I believe so.. profile!
> 
> I should.
> 
> | > One last question for now :
> | > I traverse the interesting files line-by-line and check them for a
> | > regex match, then modify the line if it matches properly.  Would it be
> | > better (faster) to read in the whole file and treat it as a single
> | > string?  Memory is not a problem.
> | 
> | Yeah, probably.. profile!
> 
> I want to speculate before I rewrite it :-).  Maybe Tim will tell me
> something (since he is so familiar with the inner workings)?
> 
> -D
> 
> -- 
> 
> How to shoot yourself in the foot with Java:
> 
> You find that Microsoft and Sun have released imcompatible class
> libraries both implementing Gun objects. You then find that although
> there are plenty of feet objects implemented in the past in many other
> languages, you cannot get access to one. But seeing as Java is so cool,
> you dont care and go around shooting anything else you can find.
>     (written by Mark Hammond)
> 
> 
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