[pypy-dev] performance problems with Krakatau

[Maciej Fijalkowski]

On Tue, Jan 14, 2014 at 11:38 PM, Robert Grosse <n210241048576 at gmail.com> wrote:
> Hi, I have been trying to use Pypy to speed up the Krakatau decompiler
> (https://github.com/Storyyeller/Krakatau). It is a large, pure Python
> application with several compute intensive parts, so I thought it would work
> well. Unfortunately, there is no clear speedup, and Pypy requires several
> times as much memory as well, making it unusual for larger inputs.
>
> For example, decompiling a quarter of ASM, I got the following results
> (execution time, memory usage)
>
> cpython 64 -  62.5s, 102.6kb
> cpython 32 -  69.2s,  54.5kb
> pypy 2.1.0 - 106.5s, 277.8kb
> pypy 2.2.1 - 109.2s, 194.6kb
>
> Sometimes, 2.2.1 is faster than 2.1.0, but they're both clearly much worse
> than CPython.
>
> These tests were performed on Windows 7 64bit using the prebuilt 32bit
> binaries of Pypy. I tested the 32bit version of CPython too, to see if the
> problem was a lack of 64bit support. However, CPython 32bit also vastly
> outperformed Pypy.
>
> Execution time was measured using time.time(). Memory usage was measured by
> watching the Windows Resource Manager and recording the peak Private value.
> Similar patterns were seen in Working Set, etc.
>
> I thought the increased memory usage at least might be explained by constant
> overhead from compiled code or from it not running long enough to trigger
> full garbage collection. However, Pypy continues to use several times as
> much memory on much larger examples.
>
> Does anyone know what could be going on here? Pypy isn't normally slower
> than CPython. Is there a way for me to tell what the problem is?

Hi.

It depends on your workload a lot. If you want us to have a look into
it, you need to provide a clear and reproducible way to run a
benchmark.

Cheers,
fijal