Re: MacOS X problem with the gui

[Daniel J Sebald]

On 08/24/2012 08:55 PM, Ben Abbott wrote:
> On Aug 24, 2012, at 11:46 AM, Ben Abbott wrote:

> > Break on 
> > __THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__()
> >  to debug.
> >
> > A description of what can cause these errors is at the link below.
> >
> > http://objectivistc.tumblr.com/post/16187948939/you-must-exec-a-core-foundation-fork-safety-tale
> >
> > Ben
> >
> > <octave_2012-08-24-114342_Bens-MacBook-Pro.crash>
>
> Same problem had been reported for gnuplot.  Anyone know how to look track down 
> the changeset?
>
> http://sourceforge.net/tracker/index.php?func=detail&aid=3469233&group_id=2055&atid=102055

The bug report says it was closed because of being out of date.  That's 
not real helpful, meaning there likely wasn't anything done to fix it 
and it went away on its own.  OR, the code is set up so that if the fork 
fails it attempts something without a fork.

There aren't any comments associated with changesets.  gnuplot maintains 
a ChangeLog of exactly what has been modified, and they are usually 
descriptive enough.  I looked and saw only one comment about fork() on 
2012-07-05.  One would then use the date to browse the diff in 
CVS/Sourceforge.  But don't do that in this case because the comment 
didn't relate to what you've found.  I will ask Mojca why that bug 
report was resolved.

Are the comments you are seeing:

__THE_PROCESS_HAS_FORKED_AND_YOU_CANNOT_USE_THIS_COREFOUNDATION_FUNCTIONALITY___YOU_MUST_EXEC__()

actual errors?  Or a limitation of your debugger?  It looks to me like 
the debugger is telling you it can't follow forks, which understandably 
might be kind of tricky because the debugger has this whole history of 
things it has done and variables it has tracked and that would mean 
replicating all that stuff.  But, exec() to the debugger might look like 
just starting an additional debug session (i.e., from scratch).

Perhaps the resolution is to not turn on debug code.

But, this issue with fork() and Qt is sort of what I'm wondering about 
Windows.  That would help gnuplot developers as this fork() in Qt might 
not be essential; it was patterned after the X11 terminal without 
thought of what fork() is for in this case.

Dan