[pypy-dev] Benchmarking PyPy performance on real-world Django app

Igor Katson igor.katson at gmail.com
Sun Oct 9 20:58:03 CEST 2011

On 10/08/2011 03:35 AM, Maciej Fijalkowski wrote:
> On Sat, Oct 8, 2011 at 1:28 AM, Igor Katson<igor.katson at gmail.com>  wrote:
>> On 10/08/2011 02:50 AM, Maciej Fijalkowski wrote:
>>> On Sat, Oct 8, 2011 at 12:48 AM, Andy<angelflow at yahoo.com>    wrote:
>>>> 15 times more memory? That's a lot.
>>>> Interestingly Quora reported that their PyPy processes were only 50%
>>>> larger
>>>> than CPython ones:
>>>> http://www.quora.com/Quora-Infrastructure/Did-Quoras-switch-to-PyPy-result-in-increased-memory-consumption
>>>> "our PyPy worker processes themselves take approximately 50% more memory
>>>> than our equivalent CPython worker processes, although we did not do a
>>>> large
>>>> amount of tuning of the GC. Regardless, this wasn't the main cause of our
>>>> memory blowup.
>>>> "In our development, we found that certain functions were not worth being
>>>> ported from their C libraries to pure Python, things like
>>>> crypto
>>>> ,
>>>> lxml
>>>> ,
>>>> PyML
>>>> , and a couple other random libraries. Our solution for those functions
>>>> was
>>>> to run a parallel CPython process that would do nothing but take
>>>> arguments
>>>> via an
>>>> execnet
>>>> channel, and output return values via the same
>>>> execnet
>>>>   channel.
>>>> "The overhead for some of these Python processes, especially for the ones
>>>> that required a lot of state (for example,
>>>> PyML
>>>> ) is comparable to the amount of memory taken by the master PyPy process,
>>>> effectively causing a 2-3x blowup in memory just to maintain the CPython
>>>> processes; this is our main memory sink for our PyPy branch."
>>>> ----
>>>> I wonder what accounts for this large difference in PyPy memory
>>>> consumption
>>>> (50% more vs. 1,400% more). What type of "large amount of tuning of the
>>>> GC"
>>>> did Quora do?
>>> I think this is a bug, but also different stack was used right?
>>> Indeed, pypy should not use much more than 2x of CPython usage, I
>>> would like to give it a go if you can come up with a small
>>> reproducible example.
>>> Cheers,
>>> fijal
>> yeah, I will send you the test suite in a while. This is a bit another
>> setup: same site with no data and sqlite instead of pypq, but it's clear
>> that the memory usage is also huge, though far more requests are needed to
>> bump memory usage to 200mb. cPython memory usage is constant.
> It *might* be the same thing as with tornado where memory usage grows
> constantly. Justin peel is working on it and it'll be in 1.7 some time
> soon (it does not have to though, but it does sound remarkably
> similar)
I tried with that branch, but there is no difference. Will you try to 
debug it with the stuff I gave you?

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