是否可以在阻塞并可能回调到 Python 的 C 函数之前释放 GIL？

发布于 2024-10-20 08:13:51 字数 497 浏览 3 评论 0原文

我正在包装一个 C 函数，该函数执行阻塞操作（选择），然后处理传入消息。我的理解是，当一个 C 函数将要阻塞时，在允许其他线程运行的同时调用它的正确方法是：

Py_BEGIN_ALLOW_THREADS                                                  
blocking_function();
Py_END_ALLOW_THREADS

但是，这个函数恰好将回调指针作为参数。在处理由 C 函数预处理的传入消息时调用此回调。我已成功将此回调包装在调用 PyEval_CallObject() 的函数中，允许我向其传递 Python 回调。

现在我正在添加线程支持，我想知道是否可以同时：

在调用此阻塞操作之前释放 GIL。
让这个阻塞操作安全地回调到 python 解释器中。

这会引起问题吗？如果是这样，有办法解决吗？

谢谢。

原文

I am wrapping a C function which performs a blocking operation (select) and then handles incoming messages. My understanding is that when a C function is going to block, the correct way to call it while allowing other threads to run is:

Py_BEGIN_ALLOW_THREADS                                                  
blocking_function();
Py_END_ALLOW_THREADS

However, it happens that this function takes as a parameter a callback pointer. This callback is called on handling the incoming message that is pre-processed by the C function. I have successfully wrapped this callback in a function which calls PyEval_CallObject(), allowing me to pass it a Python callback.

Now that I'm adding threading support, I'm wondering if it's possible to simultaneously:

Release the GIL before calling this blocking operation.
Have this blocking operation safely call back into the python interpreter.

Is this going to cause problems? If so, is there a way around it?

Thanks.

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嗳卜坏 2024-10-27 08:13:51

我几个月前使用过这些API函数，我的记忆有点模糊，但我相信这段代码会解决你的问题。我假设版本 2.x（3.x 可能不同）：（

PyGILState_STATE gstate;
gstate = PyGILState_Ensure();

/* Make your call to PyEval_CallObject() here (and any other PY API calls). */

PyGILState_Release(gstate);

以上内容取自：Python C/API 文档）

这基本上与 Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS 相反
宏。在这些函数中，您释放 GIL，但在 PyGILState 函数中您获取 GIL。

I used these API functions several months ago, and my recollection is a bit hazy, but I believe this code will solve your problem. I am assuming version 2.x (3.x may be different):

PyGILState_STATE gstate;
gstate = PyGILState_Ensure();

/* Make your call to PyEval_CallObject() here (and any other PY API calls). */

PyGILState_Release(gstate);

(The above was taken from: Python C/API docs)

This is basically the inverse of the Py_BEGIN_ALLOW_THREADS/Py_END_ALLOW_THREADS
macros. Within those, you release the GIL, but within the PyGILState functions you acquire the GIL.

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