Re: Calling into Python from a C thread
On Feb 9, 2009, at 3:59 PM, Christian Heimes wrote: Philip Semanchuk wrote: Yes, that's accurate except for the word forgot. To forget something one must first know it. =) I found the threading API documentation difficult to follow, but I suppose that what I'm doing is a little unusual so if it is not well-documented territory, that's what I get for wandering off the map. I see. Apparently the threading and embedding docs don't cover your case. The docs at http://docs.python.org/c-api/init.html#thread-state-and-the-global-interpreter-lock and http://docs.python.org/extending/embedding.html should explain how and when to initialize Python threads. Please report a documentation bug at http://bugs.python.org/. I read that several times and eventually got my code working. I wouldn't say that the documentation didn't cover my case (implementing a callback). I'd say that it doesn't cover *any* cases in particular. It's more like a list of tools for manipulating the GIL and thread state and an explanation of the need for them rather than a tutorial on how to use them. The latter is what I needed, but as I said, what I'm doing is atypical and I think it is reasonable to expect thin documentation on atypical situations. PS: I know a great way to learn more about Python's internal threading CAPI: fix your code, test it and attach a doc patch to your bug report. *hint* :) I will file a bug on a least one specific point which is that PyGILState_Ensure() acquires the GIL and PyGILState_Release() appears to release it; the latter point is undocumented. Cheers Philip -- http://mail.python.org/mailman/listinfo/python-list
Re: Calling into Python from a C thread
[posted e-mailed] In article mailman.8619.1233597806.3487.python-l...@python.org, Philip Semanchuk phi...@semanchuk.com wrote: I'm trying call Python from inside of a C thread that's running in a Python extension I've written and I am not having much luck. My C thread function consists of simply this, and I get a segmentation fault from Python: Because it's been a week without response, I suggest you try the capi mailing list. -- Aahz (a...@pythoncraft.com) * http://www.pythoncraft.com/ Weinberg's Second Law: If builders built buildings the way programmers wrote programs, then the first woodpecker that came along would destroy civilization. -- http://mail.python.org/mailman/listinfo/python-list
Re: Calling into Python from a C thread
On Feb 9, 2009, at 12:02 PM, Aahz wrote: [posted e-mailed] In article mailman.8619.1233597806.3487.python-l...@python.org, Philip Semanchuk phi...@semanchuk.com wrote: I'm trying call Python from inside of a C thread that's running in a Python extension I've written and I am not having much luck. My C thread function consists of simply this, and I get a segmentation fault from Python: Because it's been a week without response, I suggest you try the capi mailing list. I didn't know there *was* such a thing. Thanks for the tip! For those who might be interested, the list is here: http://mail.python.org/mailman/listinfo/capi-sig FYI, I got my code working and it is in the latest release of posix_ipc: http://semanchuk.com/philip/posix_ipc/ The function MessageQueue_request_notification() does some necessary setup and the function process_notification() does the rest of the work. Cheers Philip -- http://mail.python.org/mailman/listinfo/python-list
Re: Calling into Python from a C thread
Philip Semanchuk wrote: I didn't know there *was* such a thing. Thanks for the tip! For those who might be interested, the list is here: http://mail.python.org/mailman/listinfo/capi-sig FYI, I got my code working and it is in the latest release of posix_ipc: http://semanchuk.com/philip/posix_ipc/ The function MessageQueue_request_notification() does some necessary setup and the function process_notification() does the rest of the work. Let me guess. You either forgot to start Python's threading system or you didn't register you thread with Python. You need to deal with PyThread_init_thread(), PyEval_InitThreads(), PyThreadState_New(), PyThreadState_Clear() and PyThreadState_DeleteCurrent(). The module Modules/threadmodule.c contains some examples. Christian -- http://mail.python.org/mailman/listinfo/python-list
Re: Calling into Python from a C thread
On Feb 9, 2009, at 2:35 PM, Christian Heimes wrote: Philip Semanchuk wrote: I didn't know there *was* such a thing. Thanks for the tip! For those who might be interested, the list is here: http://mail.python.org/mailman/listinfo/capi-sig FYI, I got my code working and it is in the latest release of posix_ipc: http://semanchuk.com/philip/posix_ipc/ The function MessageQueue_request_notification() does some necessary setup and the function process_notification() does the rest of the work. Let me guess. You either forgot to start Python's threading system or you didn't register you thread with Python. You need to deal with PyThread_init_thread(), PyEval_InitThreads(), PyThreadState_New(), PyThreadState_Clear() and PyThreadState_DeleteCurrent(). The module Modules/threadmodule.c contains some examples. Yes, that's accurate except for the word forgot. To forget something one must first know it. =) I found the threading API documentation difficult to follow, but I suppose that what I'm doing is a little unusual so if it is not well-documented territory, that's what I get for wandering off the map. -- http://mail.python.org/mailman/listinfo/python-list
Re: Calling into Python from a C thread
Philip Semanchuk wrote: Yes, that's accurate except for the word forgot. To forget something one must first know it. =) I found the threading API documentation difficult to follow, but I suppose that what I'm doing is a little unusual so if it is not well-documented territory, that's what I get for wandering off the map. I see. Apparently the threading and embedding docs don't cover your case. The docs at http://docs.python.org/c-api/init.html#thread-state-and-the-global-interpreter-lock and http://docs.python.org/extending/embedding.html should explain how and when to initialize Python threads. Please report a documentation bug at http://bugs.python.org/. Christian PS: I know a great way to learn more about Python's internal threading CAPI: fix your code, test it and attach a doc patch to your bug report. *hint* :) -- http://mail.python.org/mailman/listinfo/python-list
Calling into Python from a C thread
Hi all,
I'm trying call Python from inside of a C thread that's running in a
Python extension I've written and I am not having much luck. My C
thread function consists of simply this, and I get a segmentation
fault from Python:
void start_routine(union sigval foo) {
PyGILState_STATE gstate;
gstate = PyGILState_Ensure();
// Calls to Python code will go here...
PyGILState_Release(gstate);
};
I added a printf() and can see that the fault happens *after* the call
to PyGILState_Release(). Apparently I'm monkeying up something
fundamental in Python, and this is really simple so I must be missing
something big.
The context is that I'm adding support for mq_notify() to my posix_ipc
extension. A process can register via mq_notify() to have a new thread
started when a message appears in a message queue. I've got this
working when my thread code is pure C, now I'm trying to add a call to
a user-specified Python function.
Thanks
Philip
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