[Tutor] jython slowness

[Alan Gauld]

> That's very strange. I timed the same loop and jython only took
about 50%
> longer than python (the timeit module from python 2.3 works fine in
jython):
> D:\Projects\CB\lib\Lib>jython timeit.py "[i for i in [1,2,3]]"
> 100000 loops, best of 3: 1.7 usec per loop

E:\Jython>jython Lib\timeit.py "[i for i in [1,2,3]]"
100000 loops, best of 3: 2.2 usec per loop

> The for loop version is considerably slower in jython, a bit slower
in python:
> D:\Projects\CB\lib\Lib>jython timeit.py -s "l=[]" "for i in [1,2,3]:
> l.append(i)"
> 100000 loops, best of 3: 4.6 usec per loop
>

E:\Jython>jython Lib\timeit.py -s "l=[]" "for i in [1,2,3]:
l.append(i)"
100000 loops, best of 3: 6.51 usec per loop

Yes, I now get exactly the same results as you (apart from the fact
my PC is slower! :-) These are the results I'd expect to see since
comprehensions are usually faster than loops.

I don't know what happened yesterday but I tried it two or three times
and the comp took ages, today its just as fast as I'd expect. Wierd.

> I use Jython 2.1 a lot and I haven't found any serious performance
problems.

Neither had I in the past, it was measurably slower but not enough
to notice in real usage. I'm starting to use Java beans a lot at work
so  I'm slowly converting from CPython to Jython and the problem
yesterday just confused me completely...

Thanks for the tests.

Alan G.