On Sun, Dec 4, 2011 at 11:37 PM, Geoffrey Irving <irv...@naml.us> wrote:
> <snip> > > Back to the bugs: here's a branch with all the changes I needed to get > rational arithmetic to work: > > https://github.com/girving/numpy > > I discovered two more after the last email. One is another simple 0 > vs. 1 bug, and another is somewhat optional: > > commit 730b05a892371d6f18d9317e5ae6dc306c0211b0 > Author: Geoffrey Irving <irv...@naml.us> > Date: Sun Dec 4 20:03:46 2011 -0800 > > After loops, check for PyErr_Occurred() even if needs_api is 0 > > For certain types of user defined classes, casting and ufunc loops > normally run without the Python API, but occasionally need to throw > an error. Currently we assume that !needs_api means no error occur. > However, the fastest way to implement such loops is to run without > the GIL normally and use PyGILState_Ensure/Release if an error occurs. > > In order to support this usage pattern, change all post-loop checks from > > needs_api && PyErr_Occurred() > > to simply > > PyErr_Occurred() > To support this properly, I think we would need to convert needs_api into an enum with this hybrid mode as another case. While it isn't done currently, I was imagining using a thread pool to multithread the trivially data-parallel operations when needs_api is false, and I suspect the PyGILState_Ensure/Release would trigger undefined behavior in a thread created entirely outside of the Python system. For comparison, I created a special mechanism for simplified multi-threaded exceptions in the nditer in the 'errmsg' parameter: http://docs.scipy.org/doc/numpy/reference/c-api.iterator.html#NpyIter_GetIterNext Worth considering is also the fact that the PyGILState API is incompatible with multiple embedded interpreters. Maybe that's not something anyone does with NumPy, though. -Mark > > Geoffrey > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion >
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