Re: Performance of PyUnicode Issue #2100

Jeff,

+1

This is fantastic work, with very readable code and corresponding algorithm
around the index translation. Looking forward to seeing it merged in!

- Jim


On Thu, Sep 11, 2014 at 2:53 PM, Jeff Allen <[email protected]> wrote:

>  I've implemented the indexing idea now, and it makes most unicode
> operations on long-ish strings a lot faster, without significantly harming
> BMP performance. Two change sets are worth a look. (I'm pushing to
> Bitbucket to avoid a whole series of merges.)
>
> The first adds the idea of index translation, but accomplishes it using
> String methods that have to count code points:
>
> https://bitbucket.org/tournesol/jython-ja/commits/191a9854396d5ba742d4b2d3179647eb632aa6d0#Lsrc/org/python/core/PyUnicode.javaT132
>
> That one is correct but slow. Then the second one provides the index that
> makes access fast.
>
> https://bitbucket.org/tournesol/jython-ja/commits/b96c8402f7baff86b86a002194a3b50d6903a04c
>
> The bug I noticed (in find) is fixed by the sequence of changes, and
> others I've found (replace, endswith, startswith) where arguments defining
> a slice were not dealt with correctly. I think I've found them all, but
> maybe not. A couple of other things I want to do:
>
> 1. speed up slicing, using the same technique, where easy. I'll try to
> resist more complex cases, like how we do strided slices, although I think
> there's scope.
>
> 2. positively reject strings that include lone surrogates of any kind. At
> present, I only catch leading surrogates without a trailing surrogate.
>
> Shout if any of this looks wrong.
>
> Jeff
>
> Jeff Allen
>
> On 02/09/2014 19:11, Jeff Allen wrote:
>
> JMH is worth the learning curve. I have quite informative benchmarks now
> for the table building and index translation. thanks for the pointer.
>
> Jeff Allen
>
> On 19/08/2014 08:15, Jeff Allen wrote:
>
> Interesting links, thanks. Caliper seems to have a good approach and
> explains itself well. I had experimented with the flags it uses to detect
> how many repeats might be needed to make recompilation stop. JMH looks
> harder to apply. (I found a tutorial elsewhere.) Overall I quite like that
> my test is in Python, but I can see uses for these either in the next phase
> and where I might have used them in the past.
>
> Jeff Allen
>
> On 17/08/2014 09:55, Indra Talip wrote:
>
> Jeff,
> Two tools that I've seen that have a reasonable reputation for being able
> to create reliable micro benchmarks on the JVM are JMH [1] and Caliper [2].
> I've not used either but my understanding is that they are suited to that
> sort of benchmarking and handle the vagaries of the JIT compiler.
>
>  [1] http://openjdk.java.net/projects/code-tools/jmh/
>  [2] https://code.google.com/p/caliper/
>
>
>
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-- 
- Jim

jim.baker@{colorado.edu|python.org|rackspace.com|zyasoft.com}
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