当我从不同的C线程调用C-API的Py_Finalize()时，我会得到一个错误输出。
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:
只有在Python 3.X（测试过3.4.2）中才会出现这种情况，而在Python 2.7中完全相同的代码没有任何问题。
下面是一个最简示例，它展示了在使用C线程时出现该问题，但当所有操作都在单个C线程上执行时则不会出现：
#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--
主函数中basic()/with_thread()的顺序并不重要，我甚至可以多次包含这些行而没有影响，每个with_thread()调用都会导致错误输出。
编辑：
将threadState更改为全局变量，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();
}
如果我不抓取全局解释器锁（GIL），这个错误就会消失，但我需要在我的库的用户之间协调一个全局值（在我的实际代码中，exec()函数可以由任何人编写，我还有更多的初始化工作要做）。您有没有关于如何使GIL抓取更像原始示例一样更隔离但仍保持线程兼容性的见解？