memory management

[Juan Declet-Barreto]

After some exception catching, I have found that my program is throwing a MemoryError exception numerous times (~7 iterations of the main loop that processes list elements) until python25\python.exe crashes (Windows XP environment).   I implemented Dave Angel's suggestions re: processing each list element (a file) as I get it. 

So my question would be how to begin troubleshooting the conditions under which the exception is raised. Is there any more information in the exception object about how much memory is being consumed, or any other indicators as to what led to the exception?

-juan

-----Original Message-----
From: Dave Angel [mailto:d at davea.name] 
Sent: Monday, November 07, 2011 1:50 PM
To: Juan Declet-Barreto
Cc: python-list at python.org
Subject: Re: memory management

On 11/07/2011 03:33 PM, Juan Declet-Barreto wrote:
> Well, I am using Python 2.5 (and the IDLE shell) in Windows XP, which ships with ESRI's ArcGIS. In addition, I am using some functions in the arcgisscripting Python geoprocessing module for geographic information systems (GIS) applications, which can complicate things. I am currently isolating standard library Python code (e.g., os.walk()) from the arcgisscripting module to evaluate in which module the environment crash is occurring.
You top-posted.  In this mailing list, one should type new information after the quoted information, not before.

Perhaps a pre-emptive strike is in order.  On the assumption that it may be a memory problem, how about you turn the app inside out.  Instead of walking the entire tree, getting a list with all the paths, and then working on the list, how about doing the work on each file as you get it.  Or even make your own generator from os.walk, so the app can call your logic on each file, and never have all the file (name)s in memory at the same time.


Generator:

def  filelist(top, criteria):
       for  a, b, c in os.walk():
              for fiile in files:
                    apply some criteria
                    yield file


Now the main app can iterate through this "list" in the usual way

for filename in filelist(top, "*.txt"):
        dosomething...



-- 

DaveA