New submission from Jean-Paul Calderone <exar...@divmod.com>: >From python-dev:
On Fri, Jan 29, 2010 at 15:04, <exar...@twistedmatrix.com> wrote: > On 10:47 pm, tjre...@udel.edu wrote: >> >> On 1/29/2010 4:19 PM, Collin Winter wrote: >>> >>> On Fri, Jan 29, 2010 at 7:22 AM, Nick Coghlan<ncogh...@gmail.com> wrote: >> >>> Agreed. We originally switched Unladen Swallow to wordcode in our >>> 2009Q1 release, and saw a performance improvement from this across the >>> board. We switched back to bytecode for the JIT compiler to make >>> upstream merger easier. The Unladen Swallow benchmark suite should >>> provided a thorough assessment of the impact of the wordcode -> >>> bytecode switch. This would be complementary to a JIT compiler, rather >>> than a replacement for it. >>> >>> I would note that the switch will introduce incompatibilities with >>> libraries like Twisted. IIRC, Twisted has a traceback prettifier that >>> removes its trampoline functions from the traceback, parsing CPython's >>> bytecode in the process. If running under CPython, it assumes that the >>> bytecode is as it expects. We broke this in Unladen's wordcode switch. >>> I think parsing bytecode is a bad idea, but any switch to wordcode >>> should be advertised widely. >> >> Several years, there was serious consideration of switching to a >> registerbased vm, which would have been even more of a change. Since I >> learned 1.4, Guido has consistently insisted that the CPython vm is not part >> of the language definition and, as far as I know, he has rejected any byte- >> code hackery in the stdlib. While he is not one to, say, randomly permute >> the codes just to frustrate such hacks, I believe he has always considered >> vm details private and subject to change and any usage thereof 'at one's own >> risk'. > > Language to such effect might be a useful addition to this page (amongst > others, perhaps): > > http://docs.python.org/library/dis.html > > which very clearly and helpfully lays out quite a number of APIs which can > be used to get pretty deep into the bytecode. If all of this is subject to > be discarded at the first sign that doing so might be beneficial for some > reason, don't keep it a secret that people need to join python-dev to learn. > Can you file a bug and assign it to me? -Brett ---------- assignee: georg.brandl components: Documentation messages: 98661 nosy: exarkun, georg.brandl severity: normal status: open title: dis module documentation gives no indication of the dangers of bytecode inspection _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue7829> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
