Changes by Yuri Bochkarev baltazar...@gmail.com:
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nosy: +Yuri.Bochkarev
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Python tracker rep...@bugs.python.org
http://bugs.python.org/issue1175
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Guido van Rossum added the comment:
readline() goes through C stdio which makes it impossible to get
non-blocking I/O right. You should be using raw os.read() calls (until
python 3000 which will remove Python's reliance on C stdio).
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nosy: +gvanrossum
resolution: - wont fix
status:
New submission from Alex Burr:
If you have made a file nonblocking using fcntl.fcntl, .readline() will
discard the start of a line if you get EGAIN. It should attach the
partial line to the exception somehow - or at least warn the user.
I observe this on 2.3.5, but the same code exists in
Sean Reifschneider added the comment:
Doesn't the exception count as warning the user?
We probably don't want to change readline to return a partial line in
this case. An exception could be added for EGAIN that includes the
partial line. Another option would be to just document the behavior
Alex Burr added the comment:
The exception would count as a warning if it wasn't EGAIN. One expects
to catch EGAIN and try again.
The current situation is unfortunate because it *nearly* works. My
scenario is: I'm driving GDB/MI via popen2.Popen3 ( gdbCommand, False,1).
It works for most GDB
Sean Reifschneider added the comment:
Why are you putting the file in non-blocking mode? Why not just reading
in blocking mode? If you want to do other work when a line is not
available, you could use select to check to see if there's data ready
via a small or 0 timeout.
Sean Reifschneider added the comment:
Arguably, you should be using select and read (instead of readline)
for this operation. That's what I've done in the past when doing
something similar. Specifically, I believe I have looped reading into a
buffer with read, and using select with a timeout
