[Boost-users] Re: Boost Graph Library and Boehm Garbage Collector

From: FBSL (fbsl_at_[hidden])
Date: 2005-04-24 10:50:46

Thanks for answering.

Stefan Strasser wrote:

> you're right, the BGL uses the default new operator to allocate memory 
> which then isn't collected of course.
> so this makes it effectively impossible to use BGL with boehm GC.
> is there a boost guideline to allocate memory only through allocators 
> which is violated here?
> (the "new" which is causing the leak(or one of your leaks?) in your 
> code is at line 278 of graph/detail/adjacency_list.hpp in version 1.32)

As a matter of facts, by modifying the snippet code and commenting out 
the add_edge() instruction, the binary no longer leaks, so the guilty 
"new" is certainly the one you point (which allocate for an edge 
property). I tried to replace it by "new (UseGC)" in order to check if 
edge properties become collectable, but unfortunately this does not 
work, binary still leaks...

Snippet code is again provided.

-- 
#include <boost/graph/adjacency_list.hpp>
#include <gc/gc_allocator.h>
#include <gc/gc_cpp.h>
#include <iostream>
#include <vector>
#include <list>
using namespace std;
using namespace boost;
namespace boost {
 struct collected_vecS {};
 struct collected_listS {};
 template <class ValueType>
 struct container_gen<collected_vecS, ValueType> {
   typedef vector<ValueType,gc_allocator<ValueType> > type;
 };
 template <class ValueType>
 struct container_gen<collected_listS, ValueType> {
   typedef list<ValueType,gc_allocator<ValueType> > type;
 };
 template <>
 struct parallel_edge_traits<collected_vecS> {
   typedef allow_parallel_edge_tag type; };
 template <>
 struct parallel_edge_traits<collected_listS> {
   typedef allow_parallel_edge_tag type; };
 namespace detail {
   template <>
   struct is_random_access<collected_vecS> {
     enum { value = true };
     typedef true_type type;
   };
 }
}
typedef adjacency_list<collected_vecS, collected_vecS, directedS,
              no_property, no_property,
              no_property, collected_listS> graph;
int
main()
{
 while(true){
   graph * g=new (UseGC) graph;
   for(unsigned int i=0; i<100; ++i){
     add_vertex(*g);
   }
   for(unsigned int i=0; i<100; ++i){
     for(unsigned int j=0; j<100; ++j){
       // if uncommented, leaks
       // add_edge(i,j,*g);
     }
   }
 }
}