Why in "std::ostream &operator<<" I have memory leaking? - c++

Question

So, I have a simple code :
main.cpp:
#include "source/core/Vector2D.h"
int main(int argc, char **argv)
{
Vector2D vector;
return 0;
}
Vector2D.h:
#ifndef VECTOR2D_H
#define VECTOR2D_H
// Стандартные библиотеки C++
#include <cmath>
#include <ostream>
class Vector2D
{
public:
Vector2D();
~Vector2D();
friend std::ostream &operator<<(std::ostream& os, const Vector2D &v);
protected:
double m_x;
double m_y;
private:
};
#endif // VECTOR2D_H
And Vector2D.cpp
#include "Vector2D.h"
Vector2D::Vector2D()
{
m_x = m_y = 0;
}
Vector2D::~Vector2D()
{
//dtor
}
std::ostream &operator<<(std::ostream& os, const Vector2D &v)
{
os<<'{'<<v.m_x<<';'<<v.m_y<<'}';
os.flush();
return os;
}
If I check this code with valgrind then :
valgrind --leak-check=full --show-leak-kinds=all ./Game
==9886== Memcheck, a memory error detector
==9886== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==9886== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==9886== Command: ./Game
==9886==
==9886==
==9886== HEAP SUMMARY:
==9886== in use at exit: 72,704 bytes in 1 blocks
==9886== total heap usage: 1 allocs, 0 frees, 72,704 bytes allocated
==9886==
==9886== 72,704 bytes in 1 blocks are still reachable in loss record 1 of 1
==9886== at 0x4C2DB8F: malloc (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==9886== by 0x4EC3EFF: ??? (in /usr/lib/x86_64-linux-gnu/libstdc++.so.6.0.21)
==9886== by 0x40104E9: call_init.part.0 (dl-init.c:72)
==9886== by 0x40105FA: call_init (dl-init.c:30)
==9886== by 0x40105FA: _dl_init (dl-init.c:120)
==9886== by 0x4000CF9: ??? (in /lib/x86_64-linux-gnu/ld-2.23.so)
==9886==
==9886== LEAK SUMMARY:
==9886== definitely lost: 0 bytes in 0 blocks
==9886== indirectly lost: 0 bytes in 0 blocks
==9886== possibly lost: 0 bytes in 0 blocks
==9886== still reachable: 72,704 bytes in 1 blocks
==9886== suppressed: 0 bytes in 0 blocks
==9886==
==9886== For counts of detected and suppressed errors, rerun with: -v
==9886== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
72 kbytes of what? What is wrong with my code or it is some compiler or std library bug?
Compiler flags :
-std=c++1y -I/usr/include/SDL2 -I"/home/maxim/workspace/Game/cppadv_game" -O0 -g3 -pedantic -pedantic-errors -Wall -Werror -c -fmessage-length=0
UPD:
It is some std library bug :
maxim#MaximPC:echo "#include <iostream>
> int main() {return 0;} " > prog.cpp
maxim#MaximPC:~/workspace/hello_world/Debug$ g++ prog.cpp -o prog
maxim#MaximPC:~/workspace/hello_world/Debug$ valgrind ./prog
==11116== Memcheck, a memory error detector
==11116== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==11116== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==11116== Command: ./prog
==11116==
==11116==
==11116== HEAP SUMMARY:
==11116== in use at exit: 72,704 bytes in 1 blocks
==11116== total heap usage: 1 allocs, 0 frees, 72,704 bytes allocated
==11116==
==11116== LEAK SUMMARY:
==11116== definitely lost: 0 bytes in 0 blocks
==11116== indirectly lost: 0 bytes in 0 blocks
==11116== possibly lost: 0 bytes in 0 blocks
==11116== still reachable: 72,704 bytes in 1 blocks
==11116== suppressed: 0 bytes in 0 blocks
==11116== Rerun with --leak-check=full to see details of leaked memory
==11116==
==11116== For counts of detected and suppressed errors, rerun with: -v
==11116== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)

Answer 1

There's no error here:
==11116== LEAK SUMMARY:
==11116== definitely lost: 0 bytes in 0 blocks
==11116== indirectly lost: 0 bytes in 0 blocks
==11116== possibly lost: 0 bytes in 0 blocks
==11116== still reachable: 72,704 bytes in 1 blocks
Its telling you that there are no lost bytes, just 72K of data globally accessable -- stuff allocated by the standard library and still accessable when the program exits. The standard library doesn't bother to delete this stuff, as it is a waste of time -- the memory is reclaimed automatically when the process exits.
Looking at the detailed summary, this looks to be memory used to load a dynamic library at startup (probably the libstc++ library)