From rpeng@stat.ucla.edu  Sat Nov  2 02:02:55 2002
From: rpeng@stat.ucla.edu (Roger Peng)
Date: Fri, 1 Nov 2002 18:02:55 -0800 (PST)
Subject: seemingly random "nesting of readline input" warnings
In-Reply-To: <x28z0coll5.fsf@biostat.ku.dk>
Message-ID: <Pine.GSO.4.10.10211011751430.255-100000@fisher.stat.ucla.edu>

Okay, I think I can reproduce this warning:  I startup R --vanilla,
then type Ctrl-C 11 times.  On my machine (RedHat Linux 7.1, Athlon 1.2Ghz
chip) the 11th Ctrl-C produces the warning.  Again, this is R 1.6.1.

When I ran R in gdb I set a break point at line 393 of src/unix/sys-std.c.
It got triggered after the 10th Ctrl-C and when I printed ReadlineStack, I
got

Breakpoint 1, pushReadline (prompt=0x8255dd8 "> ", 
    f=0x813ed70 <readline_handler>) at sys-std.c:393
393          warning("An unusual circumstance has arisen in the nesting of
readline input. Please report using bug.report()");

(gdb) print ReadlineStack
$4 = {current = 9, max = 9, fun = {0x813ed70 <readline_handler>, 
    0x813ed70 <readline_handler>, 0x813ed70 <readline_handler>, 
    0x813ed70 <readline_handler>, 0x813ed70 <readline_handler>, 
    0x813ed70 <readline_handler>, 0x813ed70 <readline_handler>, 
    0x813ed70 <readline_handler>, 0x813ed70 <readline_handler>, 
    0x813ed70 <readline_handler>}}

I hope this helps.

-roger
_______________________________
UCLA Department of Statistics
rpeng@stat.ucla.edu
http://www.stat.ucla.edu/~rpeng

On 2 Nov 2002, Peter Dalgaard BSA wrote:

> Roger Peng <rpeng@stat.ucla.edu> writes:
> 
> > Recently, while using R-patched and now R-1.6.1 (on RedHat Linux 7.1) I've
> > been getting the following warning in the course of everyday activity:
> > 
> > [... some R activity ...]
> > 
> > In addition: Warning message: 
> > An unusual circumstance has arisen in the nesting of readline input.
> > Please report using bug.report() 
> > >
> > 
> > The warning is difficult to reproduce because it seems to appear at random
> > times, usually after I enter about 100 or so commands into the console.
> > 
> > I noticed that the function which produces this warning, `pushReadline' in
> > src/unix/sys-std.c, was modified on October 16, 2002 in regards to bug
> > report PR#2165.  I can't tell if this change is the source of the warning
> > bit I don't ever recall seeing this warning on earlier versions.
> > 
> > I build R from source using the readline-devel-4.1-9 package which came
> > with my system.
> 
> Hmm. We haven't heard that one before... The way this stuff is done,
> there's always a risk that you end up with more pushes than pops. As
> far as I remember the change, it was a pretty simple index off-by-one
> thing, and clearly needed fixing on 64-bit systems, but you never know. 
> 
> If you get a bit closer to what exactly you need to do to trigger this
> please let us know. It might be something involving non-local returns,
> i.e. error conditions or hittin ctr-C. One thing you could do fairly
> easily would be to run R with the debugger: "R -d gdb", set a
> breakpoint at the warning, and tell us whether it's
> ReadlineStack.current that is getting too large or perhaps
> ReadlineStack.max getting zeroed by something.
> 
> -- 
>    O__  ---- Peter Dalgaard             Blegdamsvej 3  
>   c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
>  (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard@biostat.ku.dk)             FAX: (+45) 35327907
> 

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seemingly random "nesting of readline input" warnings
Roger Peng