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Date: Tue, 24 May 2011 14:19:52 +0200
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Subject: debugging cygwin / octave plot problem
From: marco atzeri <marco DOT atzeri AT gmail DOT com>
To: cygwin AT cygwin DOT com
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Hi,
I am trying to understand (eventually solve) the octave cygwin problem
present in cygwin-1.7.9.
http://cygwin.com/ml/cygwin/2011-03/msg00863.html

The issue arisen with

http://cygwin.com/ml/cygwin-cvs/2011-q1/msg00102.html

and it is due to the communication between octave and gnuplot.

Octave forks, execs gnuplot and communicate with gnuplot
for sending commands and receiving feedback.
The return channel is a named pipe in the form of "/tmp/oct-22xxx"

The problem seems on the return channel and octave receives EOF instead of the
expected message.

What is really making me mad is that
- if I use the internal debug mode of octave the problem disappear,
the return channels works fine.
- If I manually exec gnuplot and send command (with internal octave
popen2 / fputs /fgets) it also works
- if I try to run octave inside gdb, at plot gdb frozen and gnuplot never arise.

All these tests are performed from xterm using both 1.7.9 and the
latest cvs sources.

Have anyone suggestion how to overcome the gdb frozen behaviour ?


Marco

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