get the size of a dynamically changing file fast ?

[Mike Driscoll]

On Jan 22, 3:35 pm, Stef Mientki <stef.mien... at gmail.com> wrote:
> Mike Driscoll wrote:
> > On Jan 17, 3:56 pm, Stef Mientki <stef.mien... at gmail.com> wrote:
>
> >> hello,
>
> >> I've a program (not written in Python) that generates a few thousands
> >> bytes per second,
> >> these files are dumped in 2 buffers (files), at in interval time of 50 msec,
> >> the files can be read by another program, to do further processing.
>
> >> A program written in VB or delphi can handle the data in the 2 buffers
> >> perfectly.
> >> Sometimes Python is also able to process the data correctly,
> >> but often it can't :-(
>
> >> I keep one of the files open en test the size of the open datafile each
> >> 50 msec.
> >> I have tried
> >>     os.stat ( ....) [ ST_SIZE]
> >>     os.path.getsize ( ... )
> >> but they both have the same behaviour, sometimes it works, and the data
> >> is collected each 50 .. 100 msec,
> >> sometimes 1 .. 1.5 seconds is needed to detect a change in filesize.
>
> >> I'm using python 2.4 on winXP.
>
> >> Is there a solution for this problem ?
>
> >> thanks,
> >> Stef Mientki
>
> > Tim Golden has a method to watch for changes in a directory on his
> > website:
>
> >http://tgolden.sc.sabren.com/python/win32_how_do_i/watch_directory_fo...
>
> > This old post also mentions something similar:
>
> >http://mail.python.org/pipermail/python-list/2007-October/463065.html
>
> > And here's a cookbook recipe that claims to do it as well using
> > decorators:
>
> >http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/426620
>
> > Hopefully that will get you going.
>
> > Mike
>
> thanks Mike,
> sorry for the late reaction.
> I've it working perfect now.
> After all, os.stat works perfectly well,
> the problem was in the program that generated the file with increasing
> size,
> by truncating it after each block write, it apperently garantees that
> the file is flushed to disk and all problems are solved.
>
> cheers,
> Stef Mientki

I almost asked if you were making sure you had flushed the data to the
file...oh well.

Mike