Re: [Boost-users] boost MPI issue on windows

Subject: Re: [Boost-users] boost MPI issue on windows
From: Matthias Troyer (troyer_at_[hidden])
Date: 2010-10-26 16:33:02

On 26 Oct 2010, at 15:52, Nick Collier wrote:

> 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
> 

This seems to happen in line 73 of boost/mpi/collectives/scatter.hpp . To see where exactly this optimization issue arises, could you please add a print statement 

  std::cerr << oa.size() << std::endl;

before line 73 to print the size of the archive there.

Matthias