On Fri, Jan 27, 2012 at 2:40 AM, Stefan Behnel <stefan...@behnel.de> wrote: > Wes McKinney, 26.01.2012 18:56: >> Just wanted to bring this issue to your guys' attention in case you >> knew what was responsible for this: >> >> https://github.com/ipython/ipython/issues/1317#issuecomment-3652550 >> >> I traced down the problem (with git bisect) to a seemingly innocuous >> commit referenced in that GitHub thread. The issue seemed to only >> present itself in IPython, so likely there was some problem with >> inspecting the Cython frames for giving context around the full >> traceback. > > That's not impossible. Traceback frames behave differently in Cython for > two reasons: a) because they are only being constructed after the fact in > an error handling case, not for normal functions, and b) because Cython > doesn't have real code objects for inspection and fakes them in a rather > ad-hoc way. For example, there is currently no function signature > information in them, and line number computation doesn't use the normal > CPython way that matches the byte code position with a compressed line > table. Instead, Cython creates a new code object for a given line on the > fly and just pretends that the function starts there. This usually works > well enough for a traceback, but this kind of differences makes it quite > possible that IPython makes assumptions about inspection here that Cython > doesn't meet. > > In another thread ("AddTraceback() slows down generators"), I was proposing > to cache the code object for a given function. That would then imply > providing a (fake) byte code position map as well and would make it easier > to provide static signature information, thus improving the overall > compatibility with the code objects that CPython creates. > > Note that it's unclear without further investigation if the problem you ran > into really has to do with these internal details. I'm just raising a > possible explanation here. > > Stefan > _______________________________________________ > cython-devel mailing list > cython-devel@python.org > http://mail.python.org/mailman/listinfo/cython-devel
My curiosity about this issue was overwhelming so I profiled and tracked down what's going on. Basically looks like a bug in IPython and the fact that it appeared then disappeared depending on the Cython version was completely idiosyncratic. Should have known since the Cython commit that git bisect yielded was so innocuous. More on this here: https://github.com/ipython/ipython/issues/1317 - Wes _______________________________________________ cython-devel mailing list cython-devel@python.org http://mail.python.org/mailman/listinfo/cython-devel
