Dear all, I am finding difficulties in understanding how distributed graphs work. My graph is simple, a string-valued property, with some edges, however, right now I have only one edge... if it works. Since each process will add its own nodes, is it possible to avoid communication when adding nodes, given that each node owns its own vertices, and no overlap is possible between processes? This would save some communication avoiding re-distribution of nodes. Can I add edges concurrently? Meaning, each process adds some edges. I've only seen examples with root adding edges, but that's limiting. My last question is maybe easy. I'm adding an edge that connects two nodes, owned by different processes. Doing this results in a crash. It seems I cannot access properties with operator[] when traversing processes. I'm posting the code below, along with the *crashing* output. I hope you can help getting a grasp on PBGL! Thanks! #include <iostream> #include <string> #include <vector> #include <cmath> #include <list> #include <functional> #include <boost/config.hpp> #include <boost/mpi.hpp> #include <boost/graph/use_mpi.hpp> #include <boost/graph/distributed/mpi_process_group.hpp> #include <boost/graph/distributed/adjacency_list.hpp> #include <boost/graph/iteration_macros.hpp> using namespace boost; using boost::graph::distributed::mpi_process_group; // Useless class class str { public: str(std::string s = std::string()) : s_(s) { // NOP } template<typename Archiver> void serialize(Archiver& ar, const unsigned int /*version*/) { ar & s_; } std::string s_; }; // Allow indexing and constructing namespace boost { namespace graph { // Index based on the str class template<> struct internal_vertex_name<str> { typedef multi_index::member<str, std::string, &str::s_> type; }; // Construct with str class template<> struct internal_vertex_constructor<str> { typedef vertex_from_name<str> type; }; } } // Handy typedef boost::adjacency_list<vecS, distributedS<mpi_process_group, vecS>, bidirectionalS, str> dgraph; typedef graph_traits<dgraph>::vertex_descriptor dvertex; // START ME UP int main(int argc, const char * argv[]) { boost::mpi::environment env; boost::mpi::communicator comm; std::cout << "RANK " << comm.rank() << std::endl; comm.barrier(); dgraph g; std::vector<dvertex> descriptors; // Each rank for(int i = 0; i < 10; i++) { str s(std::to_string(i + (comm.rank() + 1) * 100)); std::cout << "rank " << comm.rank() << " adding " << s.s_ << std::endl; descriptors.push_back( add_vertex(s, g) ); } BGL_FORALL_VERTICES(v, g, dgraph) { std::cout << "V @ " << comm.rank() << " " << g[v].s_ << " local " << v.local << " owner " << v.owner << std::endl; } std::cout << ">>> NUM VERTICES " << num_vertices(g) << " NUM EDGES " << num_edges(g) << std::endl; comm.barrier(); if(comm.rank() >= 0) { int from, dest; bool letsCrash = true; if (letsCrash) { from = 1; dest = 0; } else { from = 0; dest = 0; } std::cout << "rank " << comm.rank() << " adding edge owners " << descriptors[from].owner << " - " << descriptors[dest].owner << std::endl; add_edge(descriptors[from], descriptors[dest], g); } boost::synchronize(g); BGL_FORALL_EDGES(e, g, dgraph) { std::cout << "E @ " << comm.rank() << " " << g[boost::source(e, g)].s_ << " -> " << g[boost::target(e, g)].s_ << std::endl; } return 0; } RANK 0 RANK 1 rank 0 adding 100 rank 0 adding 101 rank 1 adding 200 rank 1 adding 201 rank 0 adding 102 rank 0 adding 103 rank 1 adding 202 rank 1 adding 203 rank 0 adding 104 rank 1 adding 204 rank 0 adding 105 rank 1 adding 205 rank 1 adding 206 rank 0 adding 106 rank 0 adding 107 rank 1 adding 207 rank 0 adding 108 rank 1 adding 208 rank 0 adding 109 rank 1 adding 209 V @ 0 100 local 0 owner 0 V @ 0 201 local 1 owner 0 V @ 0 102 local 2 owner 0 V @ 0 203 local 3 owner 0 V @ 0 104 local 4 owner 0 V @ 0 205 local 5 owner 0 V @ 1 200 local 0 owner 1 V @ 1 101 local 1 owner 1 V @ 1 202 local 2 owner 1 V @ 1 103 local 3 owner 1 V @ 1 204 local 4 owner 1 V @ 1 105 local 5 owner 1 V @ 1 206 local 6 owner 1 V @ 1 107 local 7 owner 1 V @ 1 208 local 8 owner 1 V @ 0 106 local 6 owner 0 V @ 0 207 local 7 owner 0 V @ 0 108 local 8 owner 0 V @ 0 209 local 9 owner 0

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NUM VERTICES 10 NUM EDGES 0 V @ 1 109 local 9 owner 1 NUM VERTICES 10 NUM EDGES 0 rank 1 adding edge owners 0 - 1 rank 0 adding edge owners 1 - 0 Assertion failed: (v.owner == processor()), function operator[], file /usr/local/include/boost/graph/distributed/adjacency_list.hpp, line 1696. Assertion failed: (v.owner == processor()), function operator[], file /usr/local/include/boost/graph/distributed/adjacency_list.hpp, line 1696. E @ 0 201 -> E @ 1 101 -> [Senseis-MBP:40908] *** Process received signal *** [Senseis-MBP:40908] Signal: Abort trap: 6 (6)