non-blocking PIPE read on Windows

[Antonio Valentino]

"placid" <Bulkan at gmail.com> wrote in message
news:1154064385.494993.159510 at b28g2000cwb.googlegroups.com

> Hi all,
> 
> I have been looking into non-blocking read (readline) operations on
> PIPES on windows XP and there seems to be no way of doing this. Ive
> read that you could use a Thread to read from the pipe, but if you
> still use readline() wouldnt the Thread block too?

http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/440554

> What i need to do is, create a process using subprocess.Popen, where
> the subprocess outputs information on one line (but the info
> continuesly changes and its always on the same line) and read this
> information without blocking, so i can retrieve other data from the
> line i read in then put this in a GUI interface.
> 
> 
> readline() blocks until the newline character is read, but when i use
> read(X) where X is a number of bytes then it doesnt block(expected
> functionality) but i dont know how many bytes the line will be and its
> not constant so i cant use this too.
> 
> Any ideas of solving this problem?
> 
> 
> Cheers

I realized something very similar to what you described in 

http://sourceforge.net/projects/bestgui

- the subprocess2.py module realizes the non blocking I/O
- the outputparser.py module processes the output from the controlled
process and updates the progress-bar, the status-bar and the log
messages in the GUI. Incomplete lines are stored in a buffer and
processed at the next read.

ciao

-- 
Antonio Valentino



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