在c++多线程环境中嵌入python

要解决的问题：

在c++中嵌入python解释器，可以执行python脚本，且可以开启多个c++线程来并行执行python脚本。分别使用python的CAPI和结合pybind11 来使用。

测试环境：

Deepin 15.11 / Ubuntu 16.04

python3.5

 

如果使用Python CAPI， 代码如下 EmbedPyInCpp.cpp  

#include 
#include 
#include 

void Test()
{
    PyGILState_STATE gstate;
    gstate = PyGILState_Ensure();
    const char *filename = "Embed.py";
    FILE *f;
    f = fopen(filename, "r");
    PyRun_SimpleFile(f, filename);
    // PyObject *pdict = PyDict_New();
    // PyObject *pkey = PyBytes_FromString("app");
    // PyObject *pvalue = Py_BuildValue("l", 3);
    // PyDict_SetItem(pdict, pkey, pvalue);
    // long v = PyLong_AsLong(PyDict_GetItem(pdict, pkey));
    // printf("value: %d\n", v);
    fclose(f);
    PyGILState_Release(gstate);
}

struct Interpreter
{
    Interpreter()
    {
        if (initialized)
            return;
        // initialize Python
        Py_Initialize();
        // initialize thread support
        PyEval_InitThreads();
        tstate = PyEval_SaveThread();
        initialized = true;
    }

    ~Interpreter()
    {
        if (finalized)
            return;
        printf("destructed\n");
        PyEval_RestoreThread(tstate);
        Py_Finalize();
        finalized = true;
    }

private:
    static PyThreadState *tstate;
    static bool initialized;
    static bool finalized;
};
bool Interpreter::initialized = false;
bool Interpreter::finalized = false;
PyThreadState *Interpreter::tstate = NULL;
Interpreter interpreter;

int main()
{
    std::thread thrd(&Test);
    thrd.detach();
    std::thread thrd2(&Test);
    thrd2.detach();
    int i = 10;
    while (i >= 0)
    {
        printf("waiting in main thread, left: %i seconds\n", i);
        sleep(1);
        i--;
    }
}

Makefile

EmbedPyInCpp:EmbedPyInCpp.cpp
	g++ `python3-config --includes` `python3-config --ldflags` $< -o $@

.PHONY:clean
clean:
	rm -rf EmbedPyInCpp

Embed.py

import os
import time
print("current directory is %s" % os.getcwd())
for i in range(10):
    print("current time is %s" % (time.ctime()))
    time.sleep(1)

以上是使用python 的 CAPI，如果使用pybind11的话，参考如下代码：

#include 
#include 
#include 
#include 
#include 
#include "Funcs.h"

namespace py = pybind11;
using namespace py::literals;

void Test(std::shared_ptr

Funcs.h

#pragma oncce
#include 

class Math : public std::enable_shared_from_this$\{\; public:\; Math(int\; i,\; int\; j)\; :\; i(i),\; j(j)\; \{\}\; void\; show()\; \{\; printf("i:\; \%i,\; j:\; \%i,\; sum:\; \%i\backslash n",\; i,\; j,\; sum());\; \}\; int\; sum()\; \{\; return\; i\; +\; j;\; \}\; int\; i\{0\},\; j\{0\};\; \};$

PyFuncs.cp

#include 
#include 
#include "Funcs.h"

namespace py = pybind11;
using namespace py::literals;

PYBIND11_MODULE(PyFuncs, m)
{
    py::class_>(m, "Math")
        .def(py::init())
        .def_readwrite("i", &Math::i)
        .def_readwrite("j", &Math::j)
        .def("sum", &Math::sum)
        .def("show", &Math::show);
}

CMakeLists.txt

cmake_minimum_required(VERSION 2.8.12)
project(cmake_example)

set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/Lib)
set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/Lib)
set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/Bin)

add_subdirectory(pybind11)
pybind11_add_module(PyFuncs PyFuncs.cpp)

add_executable(TestEmbedPython TestEmbedPython.cpp)
target_link_libraries(TestEmbedPython PRIVATE pybind11::embed pthread)
target_include_directories(TestEmbedPython PRIVATE ${pybind11_INCLUDE_DIR})