Re: performance issues with for loop and imap/deque maxlen=0

Hi Albert:

I was going to ask for an isolated example, which might still be useful, 
but if you have a solution, that's even more interesting.

Either open an issue at bugs.jython.org and attach a patch, or make a PR 
at https://github.com/jythontools/jython . In the latter case, we will 
go via a patch because we don't (for now) master the repo at GitHub.

Actually, that's probably the next action for the project: move to GitHub.

Jeff Allen

On 16/05/2020 14:13, Albert Cardona 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 <[email protected]> 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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