我难住了。 all_gather适用于原语（例如int），但即使对于简单的 STL 容器也失败了。valgrind 声称容器未分配/初始化，但这似乎不对。
总之：
- 我用openMP做一些多线程，然后重新加入线程。
- 在串行中，我尝试
all_gather简单地std::map使用`boost::mpi::all_gather。MPI 等级不是线程。（有 2 个 MPI rank，每个 MPI rank 有 4 个线程）。 - 然后我打算做更多（孤立的）多线程。
看起来很简单......这里可能发生了什么？
主文件
#include <openmpi/mpi.h>
#include <omp.h>
#include <boost/mpi.hpp>
#include "globals.h"
int main(int argc, char* argv[])
{
int provided_MPI;
MPI_Init_thread(&argc, &argv, MPI_THREAD_MULTIPLE, &provided_MPI );
boost::mpi::environment my_boost_mpi_env(argc, argv);
boost::mpi::communicator world_MPI_boost;
world_MPI_boost_ptr = &world_MPI_boost;
// ^^^ global variable of type boost::mpi::communicator *
perform_complete_variable_elimination_schedule();
//...
}
Conn_Comp.cpp
#include <boost/mpi.hpp>
#include <boost/mpi/collectives.hpp>
#include <boost/serialization/serialization.hpp>
#include <boost/serialization/vector.hpp>
#include <boost/serialization/map.hpp>
#include "globals.h"
...
void perform_complete_variable_elimination_schedule()
{
// isolated work in parallel using OpenMP
#pragma omp parallel
{
//work
}
// SERIAL REGION (with respect to threading).
std::map<uint,uint> my_map;
std::vector< std::map<uint,uint> > vec_of_my_maps;
boost::mpi::all_gather< std::map<uint,uint> >
(*world_MPI_boost_ptr,
my_map,
vec_of_my_maps); // <--- line 293 (referenced by valgrind)
// more isolated work in parallel using OpenMP
#pragma omp parallel
{
//work
}
}
valgrind 抱怨vectorofmap 导致读取无效。但是这vector是在调用之前立即创建的all_gather- 所以它显然是在范围内而不是在并行线程区域中。选定的 valgrind 错误输出：
==12665== Use of uninitialised value of size 4
==12665== at 0x41C8D7A: boost::archive::detail::basic_iarchive::get_library_version() const (basic_iarchive.cpp:575)
==12665== by 0x41C92C6: boost::archive::detail::basic_iarchive::load_object(void*, boost::archive::detail::basic_iserializer const&) (basic_iarchive.cpp:399)
==12665== by 0x80F5696: void boost::mpi::all_gather<std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > > >(boost::mpi::communicator const&, std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > > const&, std::vector<std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > >, std::allocator<std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > > > >&) (iserializer.hpp:387)
==12665== by 0x80DEC83: Conn_Comp::perform_complete_variable_elimination_schedule() (Conn_Comp.cpp:**293**)
==12665== by 0x80C840A: main (main.cpp:695)
==12665==
==12665== Invalid read of size 2
==12665== at 0x41C8D7A: boost::archive::detail::basic_iarchive::get_library_version() const (basic_iarchive.cpp:575)
==12665== by 0x41C92C6: boost::archive::detail::basic_iarchive::load_object(void*, boost::archive::detail::basic_iserializer const&) (basic_iarchive.cpp:399)
==12665== by 0x80F5696: void boost::mpi::all_gather<std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > > >(boost::mpi::communicator const&, std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > > const&, std::vector<std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > >, std::allocator<std::map<unsigned int, unsigned int, std::less<unsigned int>, std::allocator<std::pair<unsigned int const, unsigned int> > > > >&) (iserializer.hpp:387)
==12665== by 0x80DEC83: Conn_Comp::perform_complete_variable_elimination_schedule() (main.cpp:**293**)
==12665== by 0x80C840A: main (main.cpp:695)
==12665== Address 0x3580bece is not stack'd, malloc'd or (recently) free'd
==12665==
[drosphila:12665] *** Process received signal ***
[drosphila:12665] Signal: Segmentation fault (11)
[drosphila:12665] Signal code: Address not mapped (1)
[drosphila:12665] Failing at address: 0x3580bece
[drosphila:12665] [ 0] /lib/i686/cmov/libpthread.so.0(+0xe500) [0x44f8500]
[drosphila:12665] [ 1] /usr/lib/libboost_serialization.so.1.42.0(_ZN5boost7archive6detail14basic_iarchive11load_objectEPvRKNS1_17basic_iserializerE+0x1b7) [0x41c92c7]
[drosphila:12665] [ 2] ./detect_NAHR(_ZN5boost3mpi10all_gatherISt3mapIjjSt4lessIjESaISt4pairIKjjEEEEEvRKNS0_12communicatorERKT_RSt6vectorISD_SaISD_EE+0x587) [0x80f5697]
[drosphila:12665] [ 3] ./detect_NAHR(_ZN9Conn_Comp46perform_complete_variable_elimination_scheduleEv+0x534) [0x80dec84]
[drosphila:12665] [ 4] ./detect_NAHR(main+0xf5b) [0x80c840b]
[drosphila:12665] [ 5] /lib/i686/cmov/libc.so.6(__libc_start_main+0xe6) [0x4519ca6]
[drosphila:12665] [ 6] ./detect_NAHR() [0x80c73e1]
[drosphila:12665] *** End of error message ***
我根据boost help page的推荐使用 MPI_Init_thread 。
正如我在顶部所说，如果我使用原始（即只是uint）而不是地图，那么all_gather工作正常。为什么地图会失败？ boost serialize已经有序列化 STL 容器的方法，所以这不是问题......
另请注意，将保存所有值的向量会自动调整大小all_gather（我检查了实现all_gather）以容纳所有内容。无论如何，即使我自己初始化它，它仍然失败。
最后，即使我使用一个普通的旧数组（正确分配），例如std::map<uint,uint> *，我也会遇到同样的问题。