Re: [Jython-dev] performance issues with for loop and imap/deque maxlen=0

[Adam B. <ada...@gm...>]

Hi Albert

A PR is standard. The mercurial stuff is involved in applying the final
patch but patch submitters don't need to worry about it. Dev guide here
https://jython-devguide.readthedocs.io/en/latest/

Cheers
Adam

On Sat, 16 May 2020 at 23:14, Albert Cardona <sap...@gm...> wrote:

> Hi all,
> I think I can improve the performance of imap significantly.
> Would you take pull requests at
> https://github.com/jythontools/jython/blob/master/src/org/python/modules/itertools/imap.java
>  ?
> Or should one submit patches to the mercurial repository?
> Thanks,
> Albert
>
> On May 16, 2020, at 12:09 AM, Albert Cardona <sap...@gm...> wrote:
>
> Hi all,
>
> I am seeing severe performance problems when looping over sequences
> and invoking a single method on each element of the sequence, both
> with a for loop and with an imap + deque maxlen=0 strategy. The
> baseline is clojure, which is fully typed and compiled to bytecode.
>
> The difference is staggering: 500x to 1000x (from about 1 second to 1
> millisecond).
>
> Here is a script that can run in Fiji:
>
>
> https://github.com/acardona/scripts/blob/dev/python/imagej/tests/test_looping_performance_imglib2_setOne.py
>
> The script creates an ImgLib2 image of width=512, height=512, depth=5,
> of type unsigned byte, and then loops over all pixels to invoke the
> method "setOne" on each pixel (pixels are presented as wrapped by an
> UnsignedByteType object that offers the "setOne" method). There is an
> underlying byte[] array of size 512*512*5 to the image.
>
> Why the enormous difference? Anything that can be done to mitigate this
> issue?
>
> Thank you very much.
>
> Albert
>
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