STL Memory Leak when compiling on11.00 HPUX using the aCC -AA flag

[Jeremy Lemaire]

Hello,

I am working on cross platform code that is displaying a huge memory
leak when compiled on 11.00 HPUX using the aCC -AA flag. It is not
leaking on NT, LINUX, Solaris, or HPUX without the -AA flag. In
another news group I came across some interesting (ok scarey)
information regarding memory leaks in the STL list<...> container. I
have compiled and executed the following code and verified that this
does in fact leak on my system.

#include "stdio.h"
#include "stdlib.h"
#include "malloc.h"

#include <list>
using namespace std;
template class list<int>;

int main (int argc, char *argv[])
{
list<int> list_int;
char c='r';

do
{
for ( int j = 0; j < 99999 ; j++ )
{
list_int.push_back(2);
list_int.pop_front();
}

printf ( "\nPress r to repeat, q to exit\n=>" );
c = getchar ();
}
while ( c != 'q' );

return 0;
}

STL is used throughout my code. Has anyone run into this problem? If
so could you please let me know if you have come up with a fix, patch,
or work-around. Any help would be greatly appreciated.

Regards,
Jeremy

 

[Ivan Vecerina]

....

I am working on cross platform code that is displaying a huge
memory leak when compiled on 11.00 HPUX using the aCC -AA flag.

Question: what does the -AA flag do, what do you need it for?
....

I have compiled and executed the following code and verified
that this does in fact leak on my system. ....
for ( int j = 0; j < 99999 ; j++ )
{
list_int.push_back(2);
list_int.pop_front();
} ....
STL is used throughout my code. Has anyone run into this problem? If
so could you please let me know if you have come up with a fix, patch,
or work-around. Any help would be greatly appreciated.

What is the magnitude of the memory leak that you are observing?

The code you have posted should not leak any memory if
the std::list container is decently implemented.
If it does leak memory on your platform, can you step
through the code with a debugger and analyze where the
leak comes from ?

If it is a problem with the implementation of the standard
library that you are using, maybe using an alternative
implementation such as the free STLport (www.stlport.org)
will help.


Anyway, this is not a problem with standard C++ (as it is
specific to a platform and a given compiler setting).
You may want to request support in a forum dedicated
to the compiler you are using.

Regards,
Ivan

 

[Jeremy Lemaire]

...
Question: what does the -AA flag do, what do you need it for?

JL->Thanks for the quick response Ivan. This is from HP:

Description:
The new -AA command line option enables use of the new 2.0 Standard
C++ Library, which includes the new standard conforming
("templatized") iostream library. This is the first release of the 2.0
library. It conforms to the ISO C++ standard.

...

What is the magnitude of the memory leak that you are observing?

JL->The software is used in a Call Processing environment and varies
according to call volume. The more messages processed with STL
containers the bigger the leak. In general 7-10 calls per second will
leak 2500 kbytes per hour at a constant rate until the process runs
out of memory and core dumps.

The code you have posted should not leak any memory if
the std::list container is decently implemented.
If it does leak memory on your platform, can you step
through the code with a debugger and analyze where the
leak comes from ?

JL->Here is the gdb output:

(gdb) where
#0 0x4b68 in std::list<int,std::allocator<int>>::insert
(this=0x7f7f0920,
#aggretxform#77=@0x7f7f0950,
__it={<struct std::iterator<std::bidirectional_iterator_tag,int,long,int
*,int &>> = {<No data fields>}, _C_node = 0x40004cd8},
__x=@0x7f7f0940)
at /opt/aCC/include_std/list:911
#1 0x4404 in main (argc=1, argv=0x7f7f076c) at leakcode.cpp:18
(gdb) display this
2: this = (class std::list<int,std::allocator<int> > *) 0x7f7f0920

But I am not sure how this will help. Should I attempt to modify the
std:list class?

If it is a problem with the implementation of the standard
library that you are using, maybe using an alternative
implementation such as the free STLport (www.stlport.org)
will help.

JL->Good idea, the only problem is that I only have until the end of
today to resolve this. I was hoping for a quick fix like a patch or
adding a flag to the build line. I know, wishfull thinking.

Anyway, this is not a problem with standard C++ (as it is
specific to a platform and a given compiler setting).
You may want to request support in a forum dedicated
to the compiler you are using.

JL->I tried one of the compiler forums and they refered me here.
Thanks again for the help.

 

[Ivan Vecerina]

Hi Jeremy,

"Ivan Vecerina" <ivecATmyrealboxDOTcom> wrote in message ....
But I am not sure how this will help. Should I attempt to modify the
std:list class?

Well, it is only an option if you are sure that you understand its
implementation very well.
Its code would need to be carefully reviewed and understood...

JL->Good idea, the only problem is that I only have until the end of
today to resolve this. I was hoping for a quick fix like a patch or
adding a flag to the build line. I know, wishfull thinking.

A possible workaround, if you are only using the std::list as
a queue, would be to replace this broken container with an
std::deque -- which also has the push_back/pop_front members.

JL->I tried one of the compiler forums and they refered me here.

Well, all I can say is that the code sample you posted
should not leak any memory according to the C++ standard.
I would say that the standard library implementation
you use has a bug if this is steadily leaking memory.

[NB: btw, however, the following includes are incorrect
according to the C++ standard:
#include "stdio.h"
#include "stdlib.h"
#include "malloc.h"
This should be:
#include <cstdio>
#include <cstdlib>
// and malloc is defined in cstdlib already
]

Thanks again for the help.

Sorry I can't help further...

Sincerely,
Ivan