使用线程调用Py_Finalize时AssertionError(仅限3.X)

时间:2015-01-08 16:17:19

标签: python c++ python-3.x python-c-api python-c-extension

当我从一个不同的C线程调用C-API的Py_Finalize()时,我得到一个错误输出,而不是我进行python调用。

我看到的错误是:

Exception ignored in: <module 'threading' from 'C:\\Python34-32\\Lib\\threading.py'>
Traceback (most recent call last):
  File "C:\Python34-32\Lib\threading.py", line 1289, in _shutdown
    assert tlock.locked()
AssertionError:

这只发生在Python 3.X(用3.4.2测试)中,在Python 2.7中完全相同的代码没有任何问题。

这是一个最小的例子,它显示了在使用C线程时它发生的情况,但是当一切c线程上发生了所有事情时都没有:

#include <iostream>
#include <fstream>
#include <thread>
#include <cassert>

#include <Python.h>

void make_file()
{
   std::fstream file("my_test.py", std::ios::out);
   file << 
      "import threading\n"   << 
      "def my_function():\n" << 
      "    pass\n"             ;
   file.close();
}

void exec()
{
   PyGILState_STATE gstate = PyGILState_Ensure();
   PyObject* pdict = PyDict_New();
   PyDict_SetItemString(pdict, "__builtins__", PyEval_GetBuiltins());

   PyRun_String("import my_test", Py_file_input, pdict, pdict);
   PyRun_String("my_test.my_function()", Py_file_input, pdict, pdict);
   assert(!PyErr_Occurred());
   PyGILState_Release(gstate);
}

void basic()
{
   std::cout << "--Starting Basic--" << std::endl;

   Py_Initialize();
   PyEval_InitThreads();
   PyThreadState* threadState = PyEval_SaveThread();

   exec();

   PyEval_RestoreThread(threadState);
   Py_Finalize();

   std::cout << "--Basic Complete--" << std::endl;
}

void with_thread()
{
   std::cout << "--Starting With Thread--" << std::endl;

   Py_Initialize();
   PyEval_InitThreads();
   PyThreadState* threadState = PyEval_SaveThread();

   std::thread t(exec);
   t.join();

   PyEval_RestoreThread(threadState);
   Py_Finalize();

   std::cout << "--With Thread Complete--" << std::endl;
}

int main(int argc, char* argv[])
{
   make_file();
   basic();
   with_thread();

   return 0;
}

输出

--Starting Basic--
--Basic Complete--
--Starting With Thread--
Exception ignored in: <module 'threading' from 'C:\\Python34-32\\Lib\\threading.py'>
Traceback (most recent call last):
  File "C:\Python34-32\Lib\threading.py", line 1289, in _shutdown
    assert tlock.locked()
AssertionError:
--With Thread Complete--

main中的basic()/ with_thread()调用的顺序无关紧要,我甚至可以多次包含这些行而没有任何影响,每个with_thread()调用结果都在错误输出中。

编辑:

使threadState成为全局,然后将exec更改为:

void exec()
{
   //PyGILState_STATE gstate = PyGILState_Ensure();
   PyEval_RestoreThread(threadState); 
   PyObject* pdict = PyDict_New();
   PyDict_SetItemString(pdict, "__builtins__", PyEval_GetBuiltins());

   PyRun_String("import my_test", Py_file_input, pdict, pdict);
   PyRun_String("my_test.my_function()", Py_file_input, pdict, pdict);
   assert(!PyErr_Occurred());
   //PyGILState_Release(gstate);
   threadState = PyEval_SaveThread();
}

导致错误消失,但是我有一个全局值,我需要在我的库的用户之间进行协调(在我的实际代码中,exec()函数可以由任何人编写,我有更多的初始化我跑的东西)。在保持线程兼容性的同时,有关如何使GIL像原始示例一样更加孤立的任何见解?

1 个答案:

答案 0 :(得分:2)

尝试添加

Py_DECREF(PyImport_ImportModule("threading"));

PyEval_InitThreads();