On Mon, Nov 26, 2018 at 6:12 PM Eric V. Smith <e...@trueblade.com> wrote: > I thought the important part of the proposal was to have multiple > PyHandles that point to the same PyObject (you couldn't "directly > compare handles with each other to learn about object identity"). But > I'll admit I'm not sure why this would be a win. Then of course they > couldn't be regular pointers.
Whenever PyPy passes an object from PyPy -> C, then it has to invent a "PyObject*" to represent the PyPy object. 0.1% of the time, the C code will use C pointer comparison to implement an "is" check on this PyObject*. But PyPy doesn't know which 0.1% of the time this will happen, so 100% of the time an object goes from PyPy -> C, PyPy has to check and update some global intern table to figure out whether this particular object has ever made the transition before and use the same PyObject*. 99.9% of the time, this is pure overhead, and it slows down one of *the* most common operations C extension code does. If C extensions checked object identity using some explicit operation like PyObject_Is() instead of comparing pointers, then PyPy could defer the expensive stuff until someone actually called PyObject_Is(). Note: numbers are made up and I have no idea how much overhead this actually adds. But I'm pretty sure this is the basic idea that Armin's talking about. -n -- Nathaniel J. Smith -- https://vorpus.org _______________________________________________ Python-Dev mailing list Python-Dev@python.org https://mail.python.org/mailman/listinfo/python-dev Unsubscribe: https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
