seemingly random "nesting of readline input" warnings

Peter Dalgaard BSA
02 Nov 2002 01:35:02 +0100

Roger Peng <> 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 
> >
> 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
~~~~~~~~~~ - (             FAX: (+45) 35327907
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