Boost Bimap занимает много памяти

Я смотрел в этот, но не полезно для меня.

у меня есть boost bimap где у меня есть 1 миллион записей long long int, Теоретически это занимает 1000000 * 8 * 2 байта = 16 МБ памяти. Но я обнаружил, что общий объем используемой памяти составляет 73 МБ. Я не знаю, что происходит не так.

Ниже приведен пример кода:

main.cpp

#include <iostream>
#include <map>
#include "index.h"
template<typename T>
struct MemoryMapAllocator : std::allocator<T> {
typedef typename std::allocator<T>::pointer pointer;
typedef typename std::allocator<T>::size_type size_type;
template<typename U> struct rebind { typedef MemoryMapAllocator<U> other; };

MemoryMapAllocator() {}

template<typename U>
MemoryMapAllocator(const MemoryMapAllocator<U>& u) : std::allocator<T>(u) {}

pointer allocate(size_type size, std::allocator<void>::const_pointer = 0) {
void* p = std::malloc(size * sizeof(T));
if(p == 0)
throw std::bad_alloc();
return static_cast<pointer>(p);
}
void deallocate(pointer p, size_type) {
std::free(p);
}
};

typedef std::map<void*, std::size_t, std::less<void*>,
MemoryMapAllocator<std::pair<void* const, std::size_t>>> MemoryMap;

MemoryMap& getMemoryMap() {
static MemoryMap memMap;
return memMap;
}

std::size_t totalAllocatedMemory() {
std::size_t sum = 0;
for(auto& e : getMemoryMap())
sum += e.second;
return sum;
}

void* operator new(std::size_t size) {
void* mem = std::malloc(size == 0 ? 1 : size);

if(mem == 0)
throw std::bad_alloc();

getMemoryMap()[mem] = size;
return mem;
}

void operator delete(void* mem) noexcept {
getMemoryMap().erase(mem);
std::free(mem);
}int main(){
reference_index_hash();
std::cout << "Memory allocated: " << totalAllocatedMemory() << " bytes." << std::endl;
return 0;
}

index.cpp

#include <iostream>
#include <boost/unordered_map.hpp>
#include <boost/bimap.hpp>
#include <boost/bimap/unordered_set_of.hpp>
#include <boost/bimap/unordered_multiset_of.hpp>
#include <boost/bimap/set_of.hpp>
#include <boost/bimap/multiset_of.hpp>namespace bimaps = boost::bimaps;
typedef boost::bimap<bimaps::unordered_set_of<unsigned long long int>,
bimaps::unordered_multiset_of<unsigned long long int> > bimap_reference;
typedef bimap_reference::value_type position;
bimap_reference numbers;/*
* Creating a bimap structure.
*/

int reference_index_hash(){
for (unsigned int i=0; i < 1000000; ++i ){
numbers.insert(position(i, i+10));
}
std::cout << "bimap creation....done" << std::endl;
return 0;
}

index.h

#ifndef INDEX_H_
#define INDEX_H_#include<iostream>
#include <boost/unordered_map.hpp>
#include <boost/bimap.hpp>
#include <boost/bimap/unordered_set_of.hpp>
#include <boost/bimap/unordered_multiset_of.hpp>
#include <boost/bimap/set_of.hpp>
#include <boost/bimap/multiset_of.hpp>

extern int reference_index_hash();

namespace bimaps = boost::bimaps;

typedef boost::bimap<bimaps::unordered_set_of<unsigned long long int>,
bimaps::unordered_multiset_of<unsigned long long int > > bimap_reference;
typedef bimap_reference::value_type position;
extern bimap_reference reference_index_vector;#endif /* INDEX_H_ */

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