C extension中发起新线程回调Python函数时未获取GIL导致core的演示代码

CMakeLists.txt

cmake_minimum_required(VERSION 3.3)
project(demo)

set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -O2")


set(SOURCE_FILES demo.c)


# if you could not build successfully or error occured when importing nids
# try to replace here with your real python version
set(PYVER "2.7.10_2")


string(SUBSTRING ${PYVER} 0 3 PYVER_2)
set(HOMEBREW_PY /usr/local/Cellar/python/${PYVER}/Frameworks/Python.framework/Versions/${PYVER_2})


# first try to find hombrew version of Python.h
find_path(HOME_BREW_PYHDR Python.h
        PATHS ${HOMEBREW_PY}/include/python${PYVER_2}
        NO_DEFAULT_PATH
)
# if not found, use system version
find_path(HOME_BREW_PYHDR Python.h)

include_directories(
        BEFORE SYSTEM ${HOME_BREW_PYHDR}
)

# first try to find hombrew version of libpython
find_library(HOMEBREW_PYLIB
        python${PYVER_2}
        PATHS ${HOMEBREW_PY}/lib
        NO_DEFAULT_PATH
)
# if not found, use system version
find_library(HOMEBREW_PYLIB python${PYVER_2})


add_library(demo SHARED ${SOURCE_FILES})
target_link_libraries(demo ${HOMEBREW_PYLIB})
set_target_properties(demo PROPERTIES PREFIX "" SUFFIX ".so")

demo.c

#include <Python.h>
#include <pthread.h>

static PyObject *callback_func = NULL;

void *new_thread(void *args) {
    // 每隔10ms调用一次回调函数
    PyObject *ret = NULL;
    while (1) {
        usleep(10 * 1000);
        // 注意：如果注释掉PyGILState_Ensure和PyGILState_Release
        // 重新编译后运行test.py，就会导致core
        PyGILState_STATE state = PyGILState_Ensure();
        PyObject_CallFunction(callback_func, "O", Py_None);
        PyGILState_Release(state);
    }
}

static PyObject *set_callback(PyObject *self, PyObject *args) {
    // 注册回调函数
    PyObject *pyFunc = NULL;
    if (!PyArg_ParseTuple(args, "O", &pyFunc)) {
        return NULL;
    }
    callback_func = pyFunc;
    Py_RETURN_NONE;
}

static PyObject *auto_callback(PyObject *self, PyObject *args) {
    // 发起一个后台线程来自动调用回调函数
    pthread_t mutex;
    pthread_create(&mutex, NULL, new_thread, NULL);
    pthread_detach(mutex);
    Py_RETURN_NONE;
}

static PyMethodDef DemoModuleMethods[] = {
        {
                "auto_callback",
                auto_callback,
                METH_VARARGS,
                ""
        },
        {
                "set_callback",
                set_callback,
                METH_VARARGS,
                ""
        },
        {NULL, NULL, 0, NULL}
};

PyMODINIT_FUNC initdemo(void) {
    PyEval_InitThreads();
    (void)Py_InitModule("demo", DemoModuleMethods);
}

test.py

import demo
import ctypes
from time import sleep
from threading import Thread

def call_back_func(obj):
    print "called in new thread"

def python_thread_func():
    print "called in python thread"

if __name__ == '__main__':
    # 设置回调函数
    demo.set_callback(call_back_func)
    # 调用以后台创建线程（非阻塞）
    demo.auto_callback()
    # 主线程继续执行
    while True:
        sleep(0.01)
        python_thread_func()

该示例代码在Mac OS X 10.10下编译通过，使用的是homebrew维护的Python版本。使用系统自带Python理论上也应该能够正确编译。