Author: Armin Rigo <ar...@tunes.org> Branch: Changeset: r87178:a5599ad7bcdd Date: 2016-09-17 10:56 +0200 http://bitbucket.org/pypy/pypy/changeset/a5599ad7bcdd/
Log: Put the explanation in the docstring and in the error message diff --git a/pypy/module/sys/vm.py b/pypy/module/sys/vm.py --- a/pypy/module/sys/vm.py +++ b/pypy/module/sys/vm.py @@ -253,9 +253,28 @@ from rpython.rtyper.lltypesystem import lltype, rffi return space.wrap(rffi.cast(lltype.Signed, handle)) +getsizeof_missing = """sys.getsizeof() is not implemented on PyPy. + +A memory profiler using this function is most likely to give results +inconsistent with reality on PyPy. It would be possible to have +sys.getsizeof() return a number (with enough work), but that may or +may not represent how much memory the object uses. It doesn't even +make really sense to ask how much *one* object uses, in isolation +with the rest of the system. For example, instances have maps, +which are often shared across many instances; in this case the maps +would probably be ignored by an implementation of sys.getsizeof(), +but their overhead is important in some cases if they are many +instances with unique maps. Conversely, equal strings may share +their internal string data even if they are different objects---or +empty containers may share parts of their internals as long as they +are empty. Even stranger, some lists create objects as you read +them; if you try to estimate the size in memory of range(10**6) as +the sum of all items' size, that operation will by itself create one +million integer objects that never existed in the first place. +""" + def getsizeof(space, w_object, w_default=None): - """Not implemented on PyPy.""" if w_default is None: - raise oefmt(space.w_TypeError, - "sys.getsizeof() not implemented on PyPy") + raise oefmt(space.w_TypeError, getsizeof_missing) return w_default +getsizeof.__doc__ = getsizeof_missing _______________________________________________ pypy-commit mailing list pypy-commit@python.org https://mail.python.org/mailman/listinfo/pypy-commit