如何為在 C++ 應用程序中使用 embed python 創建的新線程狀態獲取 GIL

Question

我有一個 C++ 應用程序，我們提供了一個 python 編輯器（使用 python 3.7），用戶可以在編輯器中輸入和執行 python 代碼。 以下是我們在執行用戶提供的腳本之前創建新線程狀態並使其成為當前狀態的示例代碼。

#include <python.h>

PyThreadState* globalthread;

void executescript()
{
    PyEval_SaveThread();
    PyThreadState* ts = PyThreadState_New(globalthread->interp);
    int gilstate = PyGILState_Check(); //check whether GIL is with current thread or not
    if (!gilstate)
    {
        PyEval_RestoreThread(ts);
    }
    else
    {
        
        PyThreadState_Swap(ts);
    }
    // get the thread state with which GIL is currently assigned
    PyThreadState * gilthreadstate = PyGILState_GetThisThreadState(); 
    //----> the above line return pointer to global thread state (gilthreadstate == globalthread)
    //----> which means the GIL is not acquired by the new current thread
    gilstate = PyGILState_Check(); //results in zero as GIL is not with current thread
    std::string str = "def script():\n\timport sys\n\tsys.path.append('C:\\Python\\Python37\\Lib\\site-packages')\n\tprint(sys.path)\n\timport numpy\n\tarr = numpy.array([1, 2, 3, 4, 5])\n\tprint(arr)\nscript()";
    PyRun_SimpleString(str.c_str());
    PyThreadState_Clear(ts);
    PyThreadState_DeleteCurrent();
    PyEval_RestoreThread(globalthread);
    //following stmt returns 1 as the current thread is global thread and it has GIL with it
    gilstate = PyGILState_Check(); 
}

int main()
{
    Py_Initialize();
    PyEval_InitThreads();
    globalthread = PyThreadState_Get();
    executescript();
    PyThreadState_Swap(globalthread);
    Py_FinalizeEx();
    return 0;
} 

當 PyEval_RestoreThread 或 PyThreadState_Swap 被調用時，新的當前線程不會獲取 GIL。 因此，具有import numpy或import pandas Python 腳本將以死鎖告終。 有人可以讓我知道如何為新線程狀態或代碼錯誤獲取 GIL 嗎？

Answer 1

hn-1-8e9-wheres-my-share-m的評論通過創建一個新的 C++ 線程解決了這個問題。 這是我修改后的代碼。

#include <python.h>
#include <thread>
PyThreadState* globalthread;

void execute()
{
    PyThreadState* ts = PyThreadState_New(globalthread->interp);

    int gilstate = PyGILState_Check();
    if (!gilstate)
    {
        PyEval_RestoreThread(ts);
    }
    else
    {

        PyThreadState_Swap(ts);
    }
    std::string str = "def script():\n\timport sys\n\tsys.path.append('C:\\Python\\Python37\\Lib\\site-packages')\n\tprint(sys.path)\n\timport numpy\n\tarr = numpy.array([1, 2, 3, 4, 5])\n\tprint(arr)\nscript()";
    PyRun_SimpleString(str.c_str());
    PyThreadState_Clear(ts);
    PyThreadState_DeleteCurrent();
}

int main()
{
    Py_Initialize();
    globalthread = PyThreadState_Get();
    PyEval_SaveThread();
    std::thread t(executePythonScript);
    t.join();
    PyEval_RestoreThread(globalthread);
    //PyThreadState_Swap(globalthread);
    Py_FinalizeEx();
    return 0;
}

感謝您指出帖子。