[Lemon-user] Memory error in MaxWeightedMatching?

[Alpár Jüttner]

Hi Gereon,

Thank you for reporting the issue.

May I ask you to send us a simple compilable .cc file that shows this
symptom? It would be a great help in investigating the problem.

Regards,
Alpar

On Thu, 2011-12-08 at 20:03 +0100, Gereon Kremer wrote:
> Hi,
> 
> I'm trying to use the MaxWeightedMatching class. While running the
> program seems to work properly, some errors show up when running the
> code with valgrind. I'm actually implementing a tsp heuristic
> (christofides). below is the error message that valgrind gives me.
> 
> ==20368== Memcheck, a memory error detector
> ==20368== Copyright (C) 2002-2010, and GNU GPL'd, by Julian Seward et al.
> ==20368== Using Valgrind-3.6.1-Debian and LibVEX; rerun with -h for
> copyright info
> ==20368== Command: ./main_2.exe
> ==20368==
> ==20368== Conditional jump or move depends on uninitialised value(s)
> ==20368==    at 0x4267F5: lemon::ListGraphBase::Arc::operator
> lemon::ListGraphBase::Edge() const (list_graph.h:859)
> ==20368==    by 0x42CCBA: lemon::MaxWeightedMatching<lemon::ListGraph,
> lemon::GraphExtender<lemon::ListGraphBase>::EdgeMap<int>
> >::matching(lemon::ListGraphBase::Edge const&) const (matching.h:1961)
> ==20368==    by 0x429C54: TSP::tsp() (tsp.cpp:97)
> ==20368==    by 0x402F76: main (main_2.cpp:27)
> ==20368==
> ==20368== Conditional jump or move depends on uninitialised value(s)
> ==20368==    at 0x429C57: TSP::tsp() (tsp.cpp:97)
> ==20368==    by 0x402F76: main (main_2.cpp:27)
> ==20368==
> ==20368==
> ==20368== HEAP SUMMARY:
> ==20368==     in use at exit: 0 bytes in 0 blocks
> ==20368==   total heap usage: 142,120 allocs, 142,120 frees, 9,170,970
> bytes allocated
> ==20368==
> ==20368== All heap blocks were freed -- no leaks are possible
> ==20368==
> ==20368== For counts of detected and suppressed errors, rerun with: -v
> ==20368== Use --track-origins=yes to see where uninitialised values come
> from
> ==20368== ERROR SUMMARY: 6190 errors from 2 contexts (suppressed: 4 from 4)
> 
> the corresponding part of tsp.cpp looks like this, line 97 being "if
> (m.matching(cur))". this->g is the listgraph I'm working on. p.mst is a
> set of edges that describe an mst on this graph.
> 
> 
> MaxWeightedMatching<ListGraph, ListGraph::EdgeMap<int>> m(matchg, matchw);
> m.init();
> m.start();
> m.run();
> 
> ListGraph eulerg;
> ListGraph::EdgeMap<ListGraph::Edge> eulermap(eulerg);
> ListGraph::NodeMap<ListGraph::Node> eulernodemap(eulerg);
> ListGraph::NodeMap<bool> visited(eulerg);
> 
> GraphCopy<ListGraph, ListGraph> copy2(this->g, eulerg);
> copy2.nodeCrossRef(eulernodemap);
> copy2.edgeCrossRef(eulermap);
> copy2.run();
> 
> list<ListGraph::Edge> edges;
> for (ListGraph::EdgeIt e(eulerg); e != INVALID; ++e) edges.push_back(e);
> 
> for (list<ListGraph::Edge>::iterator it = edges.begin(); it !=
> edges.end(); ++it)
> { // copy edges in matching
> 	ListGraph::Edge cur = edgemap[eulermap[*it]];
> 	if (m.matching(cur))
> 	{
> 		eulerg.addEdge(eulerg.u(*it), eulerg.v(*it));
> 	}
> 	if (p.mst->count(eulermap[*it]) == 0) eulerg.erase(*it);
> }
> 
> 
> what exactly is wrong with this code?
> (if something is wrong that has nothing to do with the actuall error,
> I'd be happy to hear this too ;-) ).
> 
> thanks,
> gereon
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