I winnowed my own code down to a simple scatter call. I get the error under release mode but not under debug. Here's the code:

namespace mpi  = boost::mpi;

int main(int argc, char **argv) {

mpi::environment env(argc, argv);

mpi::communicator world;

vector<int> out;

vector<vector<int> > in;

if (world.rank() == 0) {

for (int i = 0; i < world.size(); ++i) {

vector<int> vec(10, 12);

in.push_back(vec);

}

}

try {

mpi::scatter(world, in, out, 0);

} catch (std::exception& ex) {

std::cerr << ex.what() << std::endl;

throw ex;

}

cout << world.rank() << " : " << out.size() << endl;

}

And the error is:

ar size: 4293462132

MPI_Send: Invalid count, error stack:

MPI_Send(176): MPI_Send(buf=0x0016F78C, count=-1505164, MPI_PACKED, dest=1, tag=

2147483647, MPI_COMM_WORLD) failed

MPI_Send(101): Negative count, value is -1505164