py3k buffered IO - flush() required between read/write?

From	Genstein <genstein@invalid.invalid>
Newsgroups	comp.lang.python
Subject	py3k buffered IO - flush() required between read/write?
Date	2011-05-11 17:27 +0100
Organization	A noiseless patient Spider
Message-ID	<iqedg8$k5a$7@dont-email.me> (permalink)

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Hey all,

Apologies if this is a dumb question (self = Python noob), but under 
py3k is it necessary to flush() a file between read/write calls in order 
to see consistent results?

I ask because I have a case under Python 3.2 (r32:88445) where it does 
appear to be, on both Gentoo Linux and Windows Vista.

I've naturally read http://docs.python.org/py3k/library/io.html and 
http://docs.python.org/py3k/tutorial/inputoutput.html#reading-and-writing-files 
but could find no reference to such a requirement.

PEP 3116 suggested this might not be required in py3k and the 
implementation notes in bufferedio.c state "BufferedReader, 
BufferedWriter and BufferedRandom...share a single buffer...this enables 
interleaved reads and writes without flushing." Which seemed conclusive 
but I'm seeing otherwise.

I have a test case, which is sadly rather long: 
http://pastebin.com/xqrzKr5D It's lengthy because it's autogenerated 
from some rather more complex code I'm working on, in order to reproduce 
the issue in isolation.

Any advice and/or flames appreciated.

All the best,

	-eg.

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py3k buffered IO - flush() required between read/write? Genstein <genstein@invalid.invalid> - 2011-05-11 17:27 +0100
  Re: py3k buffered IO - flush() required between read/write? Terry Reedy <tjreedy@udel.edu> - 2011-05-11 14:24 -0400
    Re: py3k buffered IO - flush() required between read/write? Genstein <genstein@invalid.invalid> - 2011-05-11 20:08 +0100
      Re: py3k buffered IO - flush() required between read/write? Terry Reedy <tjreedy@udel.edu> - 2011-05-11 17:38 -0400
        Re: py3k buffered IO - flush() required between read/write? Genstein <genstein@invalid.invalid> - 2011-05-12 14:30 +0100
          Re: py3k buffered IO - flush() required between read/write? Terry Reedy <tjreedy@udel.edu> - 2011-05-12 15:44 -0400
            Re: py3k buffered IO - flush() required between read/write? Genstein <genstein@invalid.invalid> - 2011-05-12 21:38 +0100
      Re: py3k buffered IO - flush() required between read/write? "Martin P. Hellwig" <martin.hellwig@gmail.com> - 2011-05-11 23:24 +0000

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