On 4/2/19 10:36, Stefan Beyer wrote:
Hey everyone!
Those of you who attended or followed one of the last two winter
sprints in Leysin might know me, the others probably won't. I'm
(still) a Master's student writing my thesis on PyPy's current issue
with cross-heap cycles when using cpyext. The main point is, that they
are not collected and stay around as floating garbage, even if they
are not reachable any more. Correct me if I'm wrong, but I didn't
notice anyone else working on that topic (and/or committing something)
since I've picked it up two years ago (yeah, I know, that long ago...).
I saw that you would be working on "cpyext performance and
completeness" during the current winter sprint this week and thought
that this might also concern my thesis. So I thought I'll give you an
update.
I recently pushed my current (non-optimized, breaking-some-tests, but
more or less working) implementation of the "CPython-style"
GC-extension for cpyext. It is still in an early stage and not all
cases (legacy and non-legacy-finalizers, weakrefs) are handled.
However, I picked up some pace during the last couple of weeks and I'm
determined to finish this implementation during the following weeks
(some quirks with the tests have been haunting me, but I think I
figured most of them out by now). After that, I will implement a
second alternative implementation (to compare to, mostly for the sake
of my thesis), which will take some more time. I also added a couple
of fancy test cases (the so called "dot-tests"), so that we can test
complex object graphs a little bit easier (and also because it was
kind of cool to have another language inside PyPy/RPython, even if it
was only for the tests...), with more test cases to come (the current
ones are a bit messy). None of the new changes concerning low-latency
applications are currently integrated, but that should not be too hard.
I guess it won't make much sense for me to join you at this year's
winter sprint, especially as I won't be able to get there before
Thursday, but I might be able to join you over the IRC channel (or
some other form of communication if you like). If there is anything
that is worth discussing please let me know! Also feel free to comment
on my code, but beware that I might change some things once I try to
do some optimizations (probably not many, but at least fix the worst
issues) and make it a little bit more readable. You can find my code
on the cpyext-gc-cycle
branch.<https://bitbucket.org/pypy/pypy/commits/branch/cpyext-gc-cycle>
Looking forward to hearing from you!
Greetings,
Stefan
Hi Stefan. It has been a while, I hope all is good by you.
Recently there was some interest in looking at the work you did in the
cpyext-gc-cycle branch toward getting it merged into PyPy. Did you ever
get any further than the published code? I merged the current py3.8
branch into cpyext-gc-cycle and immediately ran into problems (see below).
It would be great to keep pushing this forward. Would you like to pick
this up again or review changes as needed?
Any thoughts?
Matti
N.B: PyUnicodeObject has tp_itemsize==0 when in reality it sometimes
allocates extra room for data [0]. My fix in [1] didn't help.
[0] https://foss.heptapod.net/pypy/pypy/-/issues/3772
[1]
https://foss.heptapod.net/pypy/pypy/-/commit/2d53e90b42a803bfac8ca1fe7b8f70433deed89e
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