[Boost-bugs] [Boost C++ Libraries] #3306: Bug in serializing MPI datatypes/classes with arrays

Subject: [Boost-bugs] [Boost C++ Libraries] #3306: Bug in serializing MPI datatypes/classes with arrays
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2009-07-30 18:53:47

#3306: Bug in serializing MPI datatypes/classes with arrays
--------------------------------+-------------------------------------------
 Reporter:  jayesh@…            |       Owner:  dgregor
     Type:  Bugs                |      Status:  new    
Milestone:  Boost 1.40.0        |   Component:  mpi    
  Version:  Boost 1.39.0        |    Severity:  Problem
 Keywords:                      |  
--------------------------------+-------------------------------------------
 Hi,
  We received a bug report from a user using BOOST_MPI + MPICH2 on windows.
 On further investigation we found that the bug seems to be in the boost
 MPI serialization code. The code in 1.39.0 does not handle serialization
 of arrays (for MPI datatypes) correctly. The following change in the boost
 header file "boost\mpi\detail\mpi_datatype_primitive.hpp" is required for
 programs that serialize arrays to behave correctly. The fix below is a
 *quick-fix*. You can integrate the following patch or fix the bug
 *correctly*. I replaced the save_array() member function (line 61-66 in
 mpi_datatype_primitive.hpp @ 1.39.0) with the code below to get my test
 case working,

 {{{

     // fast saving of arrays of MPI types
     template<class T>
     void save_array(serialization::array<T> const& x, unsigned int /*
 version */)
     {
       BOOST_ASSERT (addresses.size() > 0);
       BOOST_ASSERT (types.size() > 0);
       BOOST_ASSERT (lengths.size() > 0);
       // We don't need the array size. Pop it !
       addresses.pop_back();
       types.pop_back();
       lengths.pop_back();

       if (x.count())
         save_impl(x.address(), boost::mpi::get_mpi_datatype(*x.address()),
 x.count());
     }

 }}}

  I used the code below (Run it with 1 MPI process, mpiexec -n 1 foo.exe)
 for my testing,

 {{{

  #include <iostream>
  #include <boost/mpi/environment.hpp>
  #include <boost/mpi/communicator.hpp>

  #include <boost/serialization/array.hpp>
  #include <boost/serialization/base_object.hpp>
  #include <boost/serialization/utility.hpp>

  using namespace std;
  namespace mpi = boost::mpi;

  class TFoo
  {
 private:
     friend class boost::serialization::access;

     template<class Archive>
     void serialize(Archive & ar, const unsigned int version)
     {
         ar & a_;
         ar & d_;
         ar & f_;
         ar & foo_arr;
     }

     int      a_;
     double   d_;
     float    f_;
     int      foo_arr[5];
  public:
      TFoo(): a_(0), d_(0.0),f_(0.0){
          for(int i=0; i<5; i++){
              foo_arr[i] = i;
          }
      }
      TFoo(int a, double d, float f): a_(a),d_(d),f_(f){
          for(int i=0; i<5; i++){
              foo_arr[i] = i;
          }
      }
      TFoo(const TFoo &foo){
          a_ = foo.a_;
          d_ = foo.d_;
          f_ = foo.f_;
          for(int i=0; i<5; i++){
              foo_arr[i] = foo.foo_arr[i];
          }
      }
      void print(void ){
          std::cout << a_ << " , " << d_ << " , " << f_ << endl;
          for(int i=0; i<5; i++){
              std::cout << foo_arr[i] << " , ";
          }
          std::cout << std::endl;
      }
      void printAddresses(void){
          std::cout << &a_ << " , " << &d_ << " , " << &f_ << endl;
      }
  };

 BOOST_IS_MPI_DATATYPE(TFoo)

  class TBar
  {
 private:
     friend class boost::serialization::access;

     int  h_[2];
     TFoo q_[2];

     template<class Archive>
     void serialize(Archive & ar, const unsigned int version)
     {
         ar & h_;
         ar & q_;
     }
  public:
      TBar(){
          h_[0] = 0; h_[1] = 0;
      }
      TBar(int h_0, int h_1, TFoo q_0, TFoo q_1){
          h_[0] = h_0;
          h_[1] = h_1;
          q_[0] = q_0;
          q_[1] = q_1;
      }
      void print(void ){
          cout << h_[0] << " , " << h_[1] << endl;
          q_[0].print(); q_[1].print();
      }
      void printAddresses(void ){
          std::cout << " &h_ = " << &h_ << " &q_ = " << &q_  << std::endl;
          std::cout << &h_[0] << " , " << &h_[1] << std::endl;
          q_[0].printAddresses(); q_[1].printAddresses();
      }
  };

 BOOST_IS_MPI_DATATYPE(TBar)

  int main(int argc, char* argv[])
  {
     int i=0;
     mpi::environment env(argc, argv);
     mpi::communicator world;
     std::cout << "I am process " << world.rank() << " of " << world.size()
               << "." << std::endl;

     TFoo foo(1234, 3.14, 3.14f);
     TFoo foo_next(5678, 4.12, 4.12f);
     TBar bar(1234, 1234, foo, foo_next);

     try{
         if (world.rank() == 0)
         {
             TFoo foo1;
             TBar bar1;

             world.isend(0, 0, foo);//AV here!!!
             world.isend(0, 0, bar);//AV here!!!

             world.recv(0, 0, foo1);
             world.recv(0, 0, bar1);
             std::cout << "FOO ======================" << std::endl;
             foo1.print();
             std::cout << "BAR ======================" << std::endl;
             bar1.print();
         }
     }catch(mpi::exception &exception){
         cout << "Error :" << exception.what();
     }

     return 0;
  }

 }}}

  We recommended the user to contact BOOST MPI devs regarding the *correct*
 fix.

 Regards,

 Jayesh Krishna
 MPICH2 team

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/3306>
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