need help debugging on Windows

Tue, Nov 2, 2004 6:31 PM

Thanks to Duncan and Brian for the pointers.  I was able to run gdb under
XP, but it didn't help much.  What eventually helped is valgrind (on Linux
on ia32)!  It indicated memory leaks, and here's how the leaks occurred:

The main C function called from R has a loop over trees, and calls a
function that grows regression trees.  That function, in turns, calls a
function that loop over variables and find the best one to split on.  I
Calloc()'ed arrays in the beginning of those functions and Free() them at
the end.  What I forgot is that there were conditional return in the middle
of those functions, bypassing the Free().

Best,
Andy

From: Duncan Murdoch

On Mon, 25 Oct 2004 22:26:35 -0400, "Liaw, Andy" <andy_liaw@merck.com>
wrote :

Dear R-devel,

Apologies for bothering y'all with this seemingly perennial

question.  A

user reported problem with my most recent version of

randomForest (4.4-1),

and I was able to reproduce it with his data with R-2.0.0 patched
(2004-10-24) on WinXP Pro.  The problem is that it crashes R

on Windows.

However, it does not happen on Linux (tried SUSE ES8 on our

Opterons and

Quantian on my laptop).  On Linux, the memory usage for the

R process goes

up to about 130MB and stays there.  On Windows, the memory

usage would

increase as the number of trees are grown (which already

seem strange, as no

more memory allocation is being done as the trees are

grown), reaches about

130MB, then starts to decline, and eventually crashes the

Rgui (or Rterm)

process.  

My biggest problem is that I have not been able to get gdb

to work under

WinXPPro, thus I've been relying on Linux for debugging.

This time I'm

really baffled, as the problem does not appear on Linux.

Can anyone provide

any hint/pointer?  I (and my hair) will be very, very grateful!

No idea what's going wrong in randomForest, but I've got some hints
for debugging on

http://www.stats.uwo.ca/faculty/murdoch/software/debuggingR

I've found both the MinGW and Cygwin versions of gdb work, and use it
under insight.  It's rather painful compared to other Windows
debuggers, but it does the job.  I've never been able to get ddd
going.

Duncan Murdoch