GDB STL Memory Usage Issue

GDB STL Memory Usage Issue

[Ravi Ramaseshan]

Hi,

I observed some strange behavior with the following system that I
would like to know more about:

I'm compiling a very memory intensive C++ application that uses STL
(hashmaps of lists). Every few seconds I erase() the entire hashmap
(and the lists). When I run the program standalone and examine the
memory usage using top, I see the total virtual memory of the program
grow (sometimes to 60+MB) before the erase call and after the erase
call drop down to a few MB - which is the behavior I would expect.

However, when I run the same program through GDB, the erase() does not
seem to have any effect and the virtual memory usage keeps on rising -
which I do not understand.

I am using GCC 4.0.3, GDB 6.4 and am compiling the program with
debugging information. I would like to understand the reasons for such
a behavior of my program under GDB.

Thanks in advance,
-- 
Ravi Ramaseshan
http://www.geocities.com/ramaseshan_ravi/

" Reality is only something we believe in strongly. "

Re: GDB STL Memory Usage Issue

[Mark Kettenis]

> Date: Mon, 9 Apr 2007 19:40:58 -0400
> From: "Ravi Ramaseshan" <ramaseshan.ravi@gmail.com>
> 
> Hi,
> 
> I observed some strange behavior with the following system that I
> would like to know more about:
> 
> I'm compiling a very memory intensive C++ application that uses STL
> (hashmaps of lists). Every few seconds I erase() the entire hashmap
> (and the lists). When I run the program standalone and examine the
> memory usage using top, I see the total virtual memory of the program
> grow (sometimes to 60+MB) before the erase call and after the erase
> call drop down to a few MB - which is the behavior I would expect.
> 
> However, when I run the same program through GDB, the erase() does not
> seem to have any effect and the virtual memory usage keeps on rising -
> which I do not understand.
> 
> I am using GCC 4.0.3, GDB 6.4 and am compiling the program with
> debugging information. I would like to understand the reasons for such
> a behavior of my program under GDB.
> 
> Thanks in advance,

Smells like an operating system bug to me.

Re: GDB STL Memory Usage Issue

[Ravi Ramaseshan]

On 4/10/07, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> > Date: Mon, 9 Apr 2007 19:40:58 -0400
> > From: "Ravi Ramaseshan" <ramaseshan.ravi@gmail.com>
> >
> > Hi,
> >
> > I observed some strange behavior with the following system that I
> > would like to know more about:
> >
> > I'm compiling a very memory intensive C++ application that uses STL
> > (hashmaps of lists). Every few seconds I erase() the entire hashmap
> > (and the lists). When I run the program standalone and examine the
> > memory usage using top, I see the total virtual memory of the program
> > grow (sometimes to 60+MB) before the erase call and after the erase
> > call drop down to a few MB - which is the behavior I would expect.
> >
> > However, when I run the same program through GDB, the erase() does not
> > seem to have any effect and the virtual memory usage keeps on rising -
> > which I do not understand.
> >
> > I am using GCC 4.0.3, GDB 6.4 and am compiling the program with
> > debugging information. I would like to understand the reasons for such
> > a behavior of my program under GDB.
> >
> > Thanks in advance,
>
> Smells like an operating system bug to me.
>
>

I am running an Ubuntu system 2.6.15-28-686 kernel, if that helps
anyone explain the problem I observed.

-- 
Ravi Ramaseshan
http://www.geocities.com/ramaseshan_ravi/

" Reality is only something we believe in strongly. "

Re: GDB STL Memory Usage Issue

[Álvaro Vega García]

Hi,

On Tue, 2007-04-10 at 10:36 -0400, Ravi Ramaseshan wrote:
> On 4/10/07, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> > > Date: Mon, 9 Apr 2007 19:40:58 -0400
> > > From: "Ravi Ramaseshan" <ramaseshan.ravi@gmail.com>
> > >
> > > Hi,
> > >
> > > I observed some strange behavior with the following system that I
> > > would like to know more about:
> > >
> > > I'm compiling a very memory intensive C++ application that uses STL
> > > (hashmaps of lists). Every few seconds I erase() the entire hashmap
> > > (and the lists). When I run the program standalone and examine the
> > > memory usage using top, I see the total virtual memory of the program
> > > grow (sometimes to 60+MB) before the erase call and after the erase
> > > call drop down to a few MB - which is the behavior I would expect.
> > >
> > > However, when I run the same program through GDB, the erase() does not
> > > seem to have any effect and the virtual memory usage keeps on rising -
> > > which I do not understand.
> > >
> > > I am using GCC 4.0.3, GDB 6.4 and am compiling the program with
> > > debugging information. I would like to understand the reasons for such
> > > a behavior of my program under GDB.
> > >
> > > Thanks in advance,
> >
> > Smells like an operating system bug to me.
> >
> >
> 
> I am running an Ubuntu system 2.6.15-28-686 kernel, if that helps
> anyone explain the problem I observed.
> 
Make sure your compiler version is the same than the execution versión
libreries (see your LD_LIBRARY_PATH). I have been experimented similar
problems when a project was compiled with GCC 3.4 and executed with gcc
4.1 dynamic libraries.

Redards,
Álvaro

Re: GDB STL Memory Usage Issue

[Ravi Ramaseshan]

On 4/10/07, Jude Moersdorf <Jude.Moersdorf@pt.com> wrote:
> Is your application multi-threaded?  If so, are many threads created and
> destroyed?  Check that you don't have a bunch of zombie child threads
> that need to be reaped.
>

No, my application is single threaded.

> -----Original Message-----
> From: gdb-owner@sourceware.org [mailto:gdb-owner@sourceware.org] On
> Behalf Of Ravi Ramaseshan
> Sent: Tuesday, April 10, 2007 7:36 AM
> To: Mark Kettenis
> Cc: gdb@sourceware.org
> Subject: Re: GDB STL Memory Usage Issue
>
> On 4/10/07, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> > > Date: Mon, 9 Apr 2007 19:40:58 -0400
> > > From: "Ravi Ramaseshan" <ramaseshan.ravi@gmail.com>
> > >
> > > Hi,
> > >
> > > I observed some strange behavior with the following system that I
> > > would like to know more about:
> > >
> > > I'm compiling a very memory intensive C++ application that uses STL
> > > (hashmaps of lists). Every few seconds I erase() the entire hashmap
> > > (and the lists). When I run the program standalone and examine the
> > > memory usage using top, I see the total virtual memory of the
> program
> > > grow (sometimes to 60+MB) before the erase call and after the erase
> > > call drop down to a few MB - which is the behavior I would expect.
> > >
> > > However, when I run the same program through GDB, the erase() does
> not
> > > seem to have any effect and the virtual memory usage keeps on rising
> -
> > > which I do not understand.
> > >
> > > I am using GCC 4.0.3, GDB 6.4 and am compiling the program with
> > > debugging information. I would like to understand the reasons for
> such
> > > a behavior of my program under GDB.
> > >
> > > Thanks in advance,
> >
> > Smells like an operating system bug to me.
> >
> >
>
> I am running an Ubuntu system 2.6.15-28-686 kernel, if that helps
> anyone explain the problem I observed.
>
> --
> Ravi Ramaseshan
> http://www.geocities.com/ramaseshan_ravi/
>
> " Reality is only something we believe in strongly. "
>


-- 
Ravi Ramaseshan
http://www.geocities.com/ramaseshan_ravi/

" Reality is only something we believe in strongly. "

RE: GDB STL Memory Usage Issue

[Jude Moersdorf]

Is your application multi-threaded?  If so, are many threads created and
destroyed?  Check that you don't have a bunch of zombie child threads
that need to be reaped.

-----Original Message-----
From: gdb-owner@sourceware.org [mailto:gdb-owner@sourceware.org] On
Behalf Of Ravi Ramaseshan
Sent: Tuesday, April 10, 2007 7:36 AM
To: Mark Kettenis
Cc: gdb@sourceware.org
Subject: Re: GDB STL Memory Usage Issue

On 4/10/07, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
> > Date: Mon, 9 Apr 2007 19:40:58 -0400
> > From: "Ravi Ramaseshan" <ramaseshan.ravi@gmail.com>
> >
> > Hi,
> >
> > I observed some strange behavior with the following system that I
> > would like to know more about:
> >
> > I'm compiling a very memory intensive C++ application that uses STL
> > (hashmaps of lists). Every few seconds I erase() the entire hashmap
> > (and the lists). When I run the program standalone and examine the
> > memory usage using top, I see the total virtual memory of the
program
> > grow (sometimes to 60+MB) before the erase call and after the erase
> > call drop down to a few MB - which is the behavior I would expect.
> >
> > However, when I run the same program through GDB, the erase() does
not
> > seem to have any effect and the virtual memory usage keeps on rising
-
> > which I do not understand.
> >
> > I am using GCC 4.0.3, GDB 6.4 and am compiling the program with
> > debugging information. I would like to understand the reasons for
such
> > a behavior of my program under GDB.
> >
> > Thanks in advance,
>
> Smells like an operating system bug to me.
>
>

I am running an Ubuntu system 2.6.15-28-686 kernel, if that helps
anyone explain the problem I observed.

-- 
Ravi Ramaseshan
http://www.geocities.com/ramaseshan_ravi/

" Reality is only something we believe in strongly. "