pybind11:从Python发送MPI通信器
pybind11:从Python发送MPI通信器
提问于 2021-12-20 14:38:48
我有一个C++类，我打算从python的mpi4py接口中调用这个类，这样每个节点都会生成这个类。在C++方面，我使用的是开放MPI库(通过自制安装)和pybind11。
C++类如下所示：
#include <pybind11/pybind11.h>
#include <iostream>
#include <chrono>
#include <thread>
#include <vector>
#include <mpi.h>
// #define PyMPI_HAVE_MPI_Message 1
// #include <mpi4py/mpi4py.h>
namespace py = pybind11;
class SomeComputation
{
float multiplier;
std::vector<int> test;
MPI_Comm comm_;
public:
void Init()
{
int rank;
MPI_Comm_rank(comm_, &rank);
test.clear();
test.resize(10, rank);
}
void set_comm(MPI_Comm comm){
this->comm_ = comm;
}
SomeComputation(float multiplier_) : multiplier(multiplier_){}
~SomeComputation() { std::cout << "Destructor Called!\n"; }
float compute(float input)
{
std::this_thread::sleep_for(std::chrono::milliseconds((int)input * 10));
for (int i = 0; i != 10; ++i)
{
std::cout << test[i] << " ";
}
std::cout << std::endl;
return multiplier * input;
}
};
PYBIND11_MODULE(module_name, handle)
{
py::class_<SomeComputation>(handle, "Cpp_computation")
.def(py::init<float>()) // args of constructers are template args
.def("set_comm", &SomeComputation::set_comm)
.def("compute", &SomeComputation::compute)
.def("cpp_init", &SomeComputation::Init);
}下面是生成相同C++的python接口：
from build.module_name import *
import time
from mpi4py import MPI
comm = MPI.COMM_WORLD
rank = comm.Get_rank()
m = Cpp_computation(44.0) # send communicator to cpp
m.cpp_init()
i = 0
while i < 5:
print(m.compute(i))
time.sleep(1)
i+=1我已经尝试过"使用pybind11共享MPI通信程序“，但是我陷入了一个长期的、毫无帮助的错误(全讯息)：
[...]
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/pybind11.h:1398:22: required from 'pybind11::class_<type_, options>& pybind11::class_<type_, options>::def(const char*, Func&&, const Extra& ...) [with Func = void (SomeComputation::*)(ompi_communicator_t*); Extra = {}; type_ = SomeComputation; options = {}]'
/Users/purusharth/Documents/hiwi/pympicontroller/main.cpp:79:7: required from here
/opt/homebrew/Cellar/gcc/11.2.0_3/include/c++/11/type_traits:1372:38: error: invalid use of incomplete type 'struct ompi_communicator_t'
1372 | : public integral_constant<bool, __is_base_of(_Base, _Derived)>
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from /Users/purusharth/Documents/hiwi/pympicontroller/main.cpp:6:
/opt/homebrew/Cellar/open-mpi/4.1.2/include/mpi.h:419:16: note: forward declaration of 'struct ompi_communicator_t'
419 | typedef struct ompi_communicator_t *MPI_Comm;
| ^~~~~~~~~~~~~~~~~~~
[...]
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/pybind11.h:1398:22: required from 'pybind11::class_<type_, options>& pybind11::class_<type_, options>::def(const char*, Func&&, const Extra& ...) [with Func = void (SomeComputation::*)(ompi_communicator_t*); Extra = {}; type_ = SomeComputation; options = {}]'
/Users/purusharth/Documents/hiwi/pympicontroller/main.cpp:79:7: required from here
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/detail/descr.h:40:19: error: invalid use of incomplete type 'struct ompi_communicator_t'
40 | return {{&typeid(Ts)..., nullptr}};
| ^~~~~~~~~~
In file included from /Users/purusharth/Documents/hiwi/pympicontroller/main.cpp:6:
/opt/homebrew/Cellar/open-mpi/4.1.2/include/mpi.h:419:16: note: forward declaration of 'struct ompi_communicator_t'
419 | typedef struct ompi_communicator_t *MPI_Comm;
| ^~~~~~~~~~~~~~~~~~~
[...]
from /Users/purusharth/Documents/hiwi/pympicontroller/main.cpp:1:
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/detail/descr.h:40:42: error: could not convert '{{<expression error>, nullptr}}' from '<brace-enclosed initializer list>' to 'std::array<const std::type_info*, 3>'
40 | return {{&typeid(Ts)..., nullptr}};
| ^
| |
| <brace-enclosed initializer list>
[...]
In file included from /Users/purusharth/Documents/hiwi/pympicontroller/main.cpp:1:
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/pybind11.h: In instantiation of 'void pybind11::cpp_function::initialize(Func&&, Return (*)(Args ...), const Extra& ...) [with Func = pybind11::cpp_function::cpp_function<void, SomeComputation, ompi_communicator_t*, pybind11::name, pybind11::is_method, pybind11::sibling>(void (SomeComputation::*)(ompi_communicator_t*), const pybind11::name&, const pybind11::is_method&, const pybind11::sibling&)::<lambda(SomeComputation*, ompi_communicator_t*)>; Return = void; Args = {SomeComputation*, ompi_communicator_t*}; Extra = {pybind11::name, pybind11::is_method, pybind11::sibling}]':
[..]
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/pybind11.h:1398:22: required from 'pybind11::class_<type_, options>& pybind11::class_<type_, options>::def(const char*, Func&&, const Extra& ...) [with Func = void (SomeComputation::*)(ompi_communicator_t*); Extra = {}; type_ = SomeComputation; options = {}]'
/Users/purusharth/Documents/hiwi/pympicontroller/main.cpp:79:7: required from here
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/pybind11.h:266:73: in 'constexpr' expansion of 'pybind11::detail::descr<18, SomeComputation, ompi_communicator_t>::types()'
/Users/purusharth/Documents/hiwi/pympicontroller/pybind11/include/pybind11/pybind11.h:266:39: error: 'constexpr' call flows off the end of the function
266 | PYBIND11_DESCR_CONSTEXPR auto types = decltype(signature)::types();
| ^~~~~.def("set_comm", &SomeComputation::set_comm)的错误点
造成这些错误的原因是什么，应该如何解决？
更新:通过使用自定义类型的施法者添加下面的答案，如这个答案中所解释的。但这是唯一的办法吗？
回答 2
Stack Overflow用户
回答已采纳
发布于 2021-12-29 21:49:46
基于这个答案：https://stackoverflow.com/a/62449190/4593199
我能够通过创建自定义MPI类型的连铸机来传输MPI通信器。
#include <pybind11/pybind11.h>
#include <mpi.h>
#include <mpi4py/mpi4py.h>
namespace py = pybind11;
struct mpi4py_comm {
mpi4py_comm() = default;
mpi4py_comm(MPI_Comm value) : value(value) {}
operator MPI_Comm () { return value; }
MPI_Comm value;
};
namespace pybind11 { namespace detail {
template <> struct type_caster<mpi4py_comm> {
public:
PYBIND11_TYPE_CASTER(mpi4py_comm, _("mpi4py_comm"));
// Python -> C++
bool load(handle src, bool) {
PyObject *py_src = src.ptr();
// Check that we have been passed an mpi4py communicator
if (PyObject_TypeCheck(py_src, &PyMPIComm_Type)) {
// Convert to regular MPI communicator
value.value = *PyMPIComm_Get(py_src);
} else {
return false;
}
return !PyErr_Occurred();
}
// C++ -> Python
static handle cast(mpi4py_comm src,
return_value_policy /* policy */,
handle /* parent */)
{
// Create an mpi4py handle
return PyMPIComm_New(src.value);
}
};
}} // namespace pybind11::detail
// recieve a communicator and check if it equals MPI_COMM_WORLD
void print_comm(mpi4py_comm comm)
{
int rank;
std::vector<int> test;
MPI_Comm_rank(MPI_COMM_WORLD, &rank);
test.clear();
test.resize(10, rank);
for (int i = 0; i != 10; ++i) {
std::cout << test[i] << " ";
}
std::cout << std::endl;
}
class SomeComputation
{
float multiplier;
std::vector<int> test;
MPI_Comm comm_;
public:
void Init()
{
int rank;
MPI_Comm_rank(comm_, &rank);
test.clear();
test.resize(10, rank);
}
SomeComputation(float multiplier_) : multiplier(multiplier_){}
~SomeComputation() { std::cout << "Destructor Called!\n"; }
void set_comm(mpi4py_comm comm){
this->comm_ = comm;
}
float compute(float input)
{
// std::this_thread::sleep_for(std::chrono::milliseconds((int)input * 10));
for (int i = 0; i != 10; ++i)
{
std::cout << test[i] << " ";
}
std::cout << std::endl;
return multiplier * input;
}
};
mpi4py_comm get_comm()
{
return MPI_COMM_WORLD; // Just return MPI_COMM_WORLD for demonstration
}
PYBIND11_MODULE(native, m)
{
// import the mpi4py API
if (import_mpi4py() < 0) {
throw std::runtime_error("Could not load mpi4py API.");
}
// register the test functions
m.def("print_comm", &print_comm, "Do something with the mpi4py communicator.");
m.def("get_comm", &get_comm, "Return some communicator.");
py::class_<SomeComputation>(m, "Cpp_computation")
.def(py::init<float>()) // args of constructers are template args
.def("set_comm", &SomeComputation::set_comm)
.def("compute", &SomeComputation::compute)
.def("cpp_init", &SomeComputation::Init);
}然而，这个编译和运行成功，有更优雅的方式去做吗？
Stack Overflow用户
发布于 2021-12-29 16:03:19
使用void *作为为我成功编译的参数。它与pybind11接口兼容( MPI_Comm在任何情况下都是一个指针)。我唯一需要改变的就是：
void set_comm(void* comm){
this->comm_ = (MPI_Comm)comm;
}我还添加了MPI库并将文件夹包括到setup.py中，如下所示(根据需要用MPI实现替换文件夹)：
ext_modules = [
Pybind11Extension("module_name",
["src/main.cpp"],
include_dirs=["/etc/alternatives/mpi-x86_64-linux-gnu"],
library_dirs=["/usr/lib/x86_64-linux-gnu/openmpi/lib"],
libraries=["mpi", "mpi_cxx"],
),
]页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/70423477
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