Re: Debugging a large program

[Daniel Jacobowitz <drow at false dot org>]

On Mon, Oct 04, 2004 at 02:12:46PM -0700, Nick Savoiu wrote:
> >On Mon, Oct 04, 2004 at 01:44:55PM -0700, Nick Savoiu wrote:
> >> Hi,
> >>
> >> I'm using GDB to debug a rather large program and I'm running into memory
> >> usage problems that slow down debugging considerably. Just invoking GDB
> on
> >> the executable (without issuing 'run') results in GDB using up 450MB of
> >> memory.
> >>
> >> I think that this is caused by GDB reading in all the symbol info.
> However,
> >> the code that I'm debugging uses but a small fraction of the code that's
> >> present in the program. Can I somehow tell GDB to only load the symbols
> it
> >> needs?
> >
> >GDB already reads in only what it needs, and more lazily - however,
> >there's some information about every symbol that's needed.  450MB is
> >pretty remarkable; how big is the application?  readelf -S output would
> >be the best way to answer the question.
> 
> Here's what readelf -S says:
> 
> There are 30 section headers, starting at offset 0x57ec:
> 
>   [12] .text             PROGBITS        0804ad40 002d40 0000f0 00  AX  0
> 0 16
>   [23] .stab             PROGBITS        00000000 0034e4 0007a4 0c     24
> 0  4
>   [24] .stabstr          STRTAB          00000000 003c88 001983 00      0
> 0  1

This is an extremely small application.  I guess this is the KDE-style
everything-is-in-a-shared-library setup?

> BTW, 405MB was for gdb running to main() not just what I said above :) There
> probably are a few global variables but I don't think they should take up
> too much space.

That requires loading symbol information for all the shared libraries,
which is probably what's taking all the space.  400MB+ is a bit
unusual, but I don't know how big your libraries are.

-- 
Daniel Jacobowitz