[Python-bugs-list] [ python-Bugs-451622 ] xdrlib Packer performance-bug

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Bugs item #451622, was opened at 2001-08-16 09:29
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Category: Python Library
Group: None
>Status: Closed
>Resolution: Fixed
Priority: 5
Submitted By: Alex Martelli (aleax)
Assigned to: Nobody/Anonymous (nobody)
Summary: xdrlib Packer performance-bug

Initial Comment:
xrdlib.py's Packer class's pack_whatever functions all 
work by self.__buf = self.__buf + something.  If a 
Packer is used to pack many data items, this leads to 
degraded (quadratic) performance, like always when a 
big string is built up by such concatenation of small 
ones.  Suggested fix: have a self.__aubuf auxiliary 
list set to [] on __init__; change each concatenation 
to __buf into self.__aubuf.append(something); in 
method get_buffer, update the __buf "just in time" via 
self.__buf += ''.join(self.__aubuf), then of course 
self.__aubuf = [], before returning self.__buf to the 
caller.

This may be fixed in other ways of course, but the 
suggested fix seems very simple and safe.


Alex


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>Comment By: Martin v. Löwis (loewis)
Date: 2001-08-16 10:08

Message:
Logged In: YES 
user_id=21627

Instead of reinventing the wheel, I decided to use
cStringIO/StringIO to accumulate the bytes.
Committed as xdrlib 1.13.

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