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Memory Leak Using a Card

I cannot clear the memory of the card (I checked Valgrind ).

#include <map> class testMap { public: testMap(){} ~testMap(); void insert_map(int, int); private: std::map<int,int> _map; }; void testMap::insert_map(int i, int j){ _map.insert( pair<int, int>(i,j)); }

I tried _map.clear() , erase() , deleted _map->second manually, but did not succeed yet.

Thanks for all the answers. In fact, map itself is not a problem, but a map with a singleton cause causes a leak. What is wrong with the code below?

 #include <iostream> #include <string> #include <map> #include <algorithm> #include "Object.h" #include<boost/smart_ptr.hpp> using namespace std; class Singleton { public: // A wrapper around Object class class object { public: object() : _object(new Object()) {} Object get(void) { return _object.get(); } private: boost::shared_ptr<Object> _object; }; object insert_new(const std::string key) { _object_maps.insert( pair<string,object>( key, object() )); return _object_maps.find( key )->second; //_test_object = object(); //return _test_object; // Leak goes away if I don't use map. } static Singleton* Instance(); void Print(); protected: Singleton(){} ~Singleton(); private: static Singleton* _instance; std::map<std::string, object > _object_maps; object _test_object; }; Singleton* Singleton::_instance = 0; Singleton* Singleton::Instance() { if( _instance ==0 ) { _instance = new Singleton(); } return _instance; } void Singleton::Print() { std::cout << " Hi I am a singleton object" << std::endl; } Singleton::~Singleton() { _object_maps.clear(); }

From another code that I called

  Singleton::object _test_object(Singleton::Instance()->insert_new("TEST"));

Is there a problem? I get Valgrind error like

  ==19584== 17 bytes in 1 blocks are possibly lost in loss record 31,429 of 52,291 ==19584== at 0x69A1642: operator new(unsigned int) (vg_replace_malloc.c:255) ==19584== by 0x772CB0A: std::string::_Rep::_S_create(unsigned int, unsigned int, std::allocator<char> const&) (in /usr/lib/libstdc++.so.6.0.8) ==19584== by 0x772D904: ??? (in /usr/lib/libstdc++.so.6.0.8) ==19584== by 0x772DB16: std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, std::allocator<char> const&) (in /usr/lib/libstdc++.so.6.0.8) ==19584== by 0xBF1BC17: test::test() (test.C:34) ==19584== by 0xBF1DB66: G__testDict_143_0_1(G__value*, char const*, G__param*, int) (testDict.C:190) ==19584== by 0x70EA4E5: Cint::G__ExceptionWrapper(int (*)(G__value*, char const*, G__param*, int), G__value*, char*, G__param*, int) (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x71EF2E4: G__call_cppfunc (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x71C0095: G__interpret_func (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x71AF883: G__getfunction (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x71D8CC1: G__new_operator (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x718D07F: G__getexpr (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x717724E: G__define_var (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x71FDEC6: G__defined_type (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x7201A6D: G__exec_statement (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x71BF6C8: G__interpret_func (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x71AF62F: G__getfunction (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x718437D: G__getitem (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x7189F12: G__getexpr (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so) ==19584== by 0x719713F: G__calc_internal (in /afs/rhic.bnl.gov/@sys/opt/phenix/root-5.17.01/lib/libCint.so)
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2 answers

Short answer :
You explicitly declared, but did not define a destructor (forgot {} ).

Long answer :

  • Your code does not even compile. Missing {} in the class destructor and std:: before pair .

  • Fixed and completed using main :

     #include <map> class testMap { public: testMap() {} ~testMap() {}; void insert_map(int, int); private: std::map<int,int> _map; }; void testMap::insert_map(int i, int j) { _map.insert(std::pair<int, int>(i,j)); } int main() { testMap t; t.insert_map(12, 34); return 0; }

  • Compiled on 32-bit Ubuntu 11.04:

     g++ leak.cpp -o leak

  • Run on valgrind observation:

     valgrind ./leak ==20773== Memcheck, a memory error detector ==20773== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al. ==20773== Using Valgrind-3.6.1 and LibVEX; rerun with -h for copyright info ==20773== Command: ./leak ==20773== ==20773== ==20773== HEAP SUMMARY: ==20773== in use at exit: 0 bytes in 0 blocks ==20773== total heap usage: 1 allocs, 1 frees, 24 bytes allocated ==20773== ==20773== All heap blocks were freed -- no leaks are possible ==20773== ==20773== For counts of detected and suppressed errors, rerun with: -v ==20773== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 17 from 6)

  • No memory leak.

Your compiler will probably automatically detect a completely empty class destructor (due to the lack of {} ), rather than automatically invoking more when exiting the private member destructor.

Hope this helps :)

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Try:

 { std::map<int,int> empty_map; empty_map.swap(_map); }

(At the very least, this is the usual way to convince a standard library container to actually free its memory.)

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