Re: [Boost-users] [mpi/serialization] Potential bug or just library misunderstanding?

Subject: Re: [Boost-users] [mpi/serialization] Potential bug or just library misunderstanding?
From: Matthias Troyer (troyer_at_[hidden])
Date: 2011-10-19 13:59:47

On Sep 30, 2011, at 5:18 PM, Tim Jacobs wrote:

> I'm not sure why the following test-class produces this error: "MPI_Recv: MPI_ERR_TRUNCATE: message truncated"
> 
> If the std::map has only a single element (ie I remove one of the test[].push_back() lines) the error does not occur. Can someone verify that this is indeed a bug and not just novice misuse of the library?
> 
> Thanks,
> Tim
> 
> #include <boost/mpi.hpp>
> #include <boost/serialization/string.hpp>
> #include <boost/serialization/vector.hpp>
> #include <boost/serialization/map.hpp>
> 
> int
> main( int argc, char * argv [] )
> {
>   boost::mpi::environment env(argc, argv);
>   boost::mpi::communicator world;
> 
>   if(world.rank()==0){
>       std::map<int, std::vector<std::string> > test;
>       test[1].push_back("FOO");
>       test[50].push_back("BAR");
>       world.send(1, 1, boost::mpi::skeleton(test));
>       world.send(1, 1, boost::mpi::get_content(test));
>       std::cout << "sent" << std::endl;
>   }
>   else{
>       std::map<int, std::vector<std::string> > test;
>       world.recv(0,1,boost::mpi::skeleton(test));
>       world.recv(0,1,boost::mpi::get_content(test));
>   }
> }

The problem is that a std::map cannot be sent using the skeleton&content approach, since the keys need to be known to build a map.

Matthias