【发布时间】：2018-10-02 03:58:27
【问题描述】：
问题
我正在尝试找到一种通过 MPI 发送自定义序列化对象（不是自定义 MPI 结构 - 参见下面的定义）的正确方法。在阅读了一些材料和 stackoverflow 之后，我有一个使用boost::serialization 并将序列化对象作为stringstream 发送的工作 示例。但是，我当前的解决方案看起来有点hackish，请参见下面的快照（完整代码附在末尾部分）。
我的问题：您能否对当前的解决方案发表意见并推荐一些行业接受的方式来发送自定义序列化对象？
.
限制：不幸的是，
boost.mpi不是一个选项，因为它与openmpi的依赖关系在我的ubuntu-xenial基础架构上有一个与 TCP 相关的错误。我只使用纯mpich。
自定义对象定义
自定义对象：在我的示例中，自定义对象序列化其
base类、std::vector、boost::shared_ptr和其他一些简单变量。
MPI 发送/接收快照
这是我如何发送/接收流的小程序快照。
if (rank == 1) {
std::stringstream mystream;
//...more serialization code here
int len = mystream.str().size();
MPI_Send( &len, 1, MPI_INT, 1, lentag, MPI_COMM_WORLD );
MPI_Send( (void *)mystream.str().c_str(), len, MPI_BYTE, 1, datatag, MPI_COMM_WORLD );
} else if (rank == 1) {
int len;
MPI_Recv( &len, 1, MPI_INT, 0, lentag, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
char data[len+1];
MPI_Recv( data, len, MPI_BYTE, 0, datatag, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
data[len] = '\0';
std::stringstream mystream;
mystream.write((const char*) data, len);
//...more deserialization code here
}
程序输出
这是程序输出。可以看到数据从rank 0转移到rank 1成功了。
$ mpirun.mpich -np 2 ./mpidata
Rank 0 sum in 6
Rank 0 vsize out 4
Rank 0 ptr out 30
Rank 1 sum in 6
Rank 1 vsize in 4
Rank 1 ptr in 30
MPI 发送/接收完整代码
下面提供了完整的代码。
#include <mpi.h>
#include <iostream>
#include <sstream>
#include <vector>
#include <boost/archive/binary_oarchive.hpp>
#include <boost/archive/binary_iarchive.hpp>
#include <boost/serialization/base_object.hpp>
#include <boost/serialization/shared_ptr.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/serialization/string.hpp>
#include <boost/shared_ptr.hpp>
#include <boost/make_shared.hpp>
// Forward declaration of class boost::serialization::access
namespace boost {
namespace serialization {
class access;
}
}
class Obj {
public:
// Serialization expects the object to have a default constructor
Obj() : d1_(-1), d2_(-2) {}
Obj(int d1, int d2) : d1_(d1), d2_(d2) {}
bool operator==(const Obj& o) const {
return d1_ == o.d1_ && d2_ == o.d2_;
}
const int sum() const {return d1_+d2_;}
private:
int d1_;
int d2_;
// Allow serialization to access non-public data members.
friend class boost::serialization::access;
template<typename Archive>
void serialize(Archive& ar, const unsigned version) {
ar & d1_ & d2_; // Simply serialize the data members of Obj
}
};
class ObjChild : public Obj {
private:
typedef Obj _Super;
public:
ObjChild() : Obj(),d1_(-1),dv_{1,2},iptr_(new Obj()) {}
ObjChild(
int d1,
int d2,
int d1new,
std::vector<int> const& dv,
boost::shared_ptr<Obj> const& obj
) : Obj(d1,d2),d1_(d1new),dv_(dv),iptr_(obj) {}
const int sum2() const {return d1_ + sum();}
const int vsize() const {return dv_.size();}
const int ptrsum() const {return iptr_->sum();}
private:
int d1_; // Another d1_
std::vector<int> dv_;
boost::shared_ptr<Obj> iptr_;
// -------------------------------------------------------------
friend class boost::serialization::access;
template <typename Archive>
void serialize(Archive& ar, const unsigned version) {
ar & boost::serialization::base_object<_Super>(*this);
ar & d1_;
ar & dv_;
ar & iptr_;
}
// -------------------------------------------------------------
};
int main(int argc,char** argv) {
int size, rank;
MPI_Init(&argc, &argv);
MPI_Comm_size(MPI_COMM_WORLD, &size);
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
if (size < 2) {
if (rank == 0)
std::cerr << "Require at least 2 tasks" << std::endl;
MPI_Abort(MPI_COMM_WORLD, 1);
}
const int lentag=0;
const int datatag=1;
if (rank == 0) {
std::stringstream mystream;
ObjChild obj(1,3,2,{1,2,3,4},boost::make_shared<Obj>(10,20));
boost::archive::binary_oarchive oarchive{mystream};
oarchive << obj;
std::cout<<"Rank "<< rank << " sum in " << obj.sum2() << std::endl;
std::cout<<"Rank "<< rank << " vsize out " << obj.vsize() << std::endl;
std::cout<<"Rank "<< rank << " ptr out " << obj.ptrsum() << std::endl;
int len = mystream.str().size();
// Send length, then data
MPI_Send( &len, 1, MPI_INT, 1, lentag, MPI_COMM_WORLD );
MPI_Send( (void *)mystream.str().c_str(), len, MPI_BYTE, 1, datatag, MPI_COMM_WORLD );
} else if (rank == 1) {
int len;
MPI_Recv( &len, 1, MPI_INT, 0, lentag, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
char data[len+1];
MPI_Recv( data, len, MPI_BYTE, 0, datatag, MPI_COMM_WORLD, MPI_STATUS_IGNORE);
data[len] = '\0';
std::stringstream mystream;
mystream.write((const char*) data, len);
boost::archive::binary_iarchive iarchive(mystream);
ObjChild obj;
iarchive >> obj;
std::cout<<"Rank "<< rank << " sum in "<< obj.sum2() << std::endl;
std::cout<<"Rank "<< rank << " vsize in " << obj.vsize() << std::endl;
std::cout<<"Rank "<< rank << " ptr in " << obj.ptrsum() << std::endl;
}
MPI_Finalize();
return EXIT_SUCCESS;
}
【问题讨论】：
-
感谢您提供完整的代码示例。虽然这个问题很好并且可以回答，但请注意不要邀请自以为是的答案（“最佳实践”）。而是专注于切实的目标和具体问题，例如如何使用更简洁的“不那么老套”的抽象？
标签： c++ serialization boost mpi