[Boost-users] distributed breadth first search doesn't work properly?

Subject: [Boost-users] distributed breadth first search doesn't work properly?
From: Mattia Lambertini (mat.lambertini_at_[hidden])
Date: 2010-12-08 04:49:54

Hi, i am new to boost and i'm using the PBGL to write a software that compute 
some graph analysis. I've installed boost 1.44.0 and openmpi 1.5

I tried to run the breadth first search example located in 
$BOOST_ROOT/libs/graph_parallel/example

with the graph $BOOST_ROOT/libs/graph/test/weighted_graph.gr

All went well since i figure out that the result is different if i run the 
algorithm with a different number of processors.
Only with one processor the values are corrected.

here's what happens:

mpirun -np 1 ./breadth_first_search.out

graph g {
  subgraph cluster_0 {
    label="p0";
    n0[label=0];
    n1[label=2];
    n2[label=1];
    n3[label=2];
    n4[label=1];
  }

  n0 -- n2;
  n1 -- n1;
  n1 -- n3;
  n1 -- n4;
  n2 -- n1;
  n2 -- n3;
  n3 -- n4;
  n4 -- n0;
  n4 -- n1;
}

---------------------

mpirun -np 2 ./breadth_first_search.out

graph g {
  subgraph cluster_0 {
    label="p0";
    n0[label=0];
    n1[label=1];
    n2[label=1];
  }

  n0 -- n2;
  n1 -- n1;
  n1 -- n3;
  n1 -- n4;
  n2 -- n1;
  n2 -- n3;

  subgraph cluster_1 {
    label="p1";
    n3[label=1];
    n4[label=0];
  }

  n3 -- n4;
  n4 -- n0;
  n4 -- n1;
}

Is that correct? 
From the doc i can't figure out why..

-- 
Cordiali saluti,
Mattia Lambertini