[pypy-dev] Sorting structs

[Leonardo Santagada]

Can you start by having a stable benchmark? Instead of calling random have
a reverse counter to create your list in reverse order. That will at least
get somewhat similar work on both languages (javascript random is
notoriously bad at being random).

Maybe the difference in performance is all from the difference in the
distribution of the numbers. Also try bigger/smaller lists to see how they
behave. (also warming up both jit engines might be necessary)


On Mon, Sep 26, 2016 at 10:57 PM, Tuom Larsen <tuom.larsen at gmail.com> wrote:

> Dear list!
>
> I stumbled upon a problem and I was wondering if someone would by so
> kind and explain to me what is going on.
>
> The problem is sorting 2 000 000 points by `x` coordinate:
>
>     from random import random
>     from time import time
>
>     class point(object):
>         def __init__(self, x, y):
>             self.x, self.y = x, y
>
>     data = [point(random(), random()) for i in range(2000000)]
>
>     t = time()
>     data.sort(key=lambda p:p.x)
>     print time() - t
>
> on my machine in runs 8.74s under PyPy 5.4.1 on MacOS. I then try to
> sort the points in JavaScript:
>
>     var data = [];
>     for (var i=0; i<2000000; i++) {
>         data.push({x:Math.random(), y:Math.random()});
>     }
>
>     console.time('sorting');
>     data.sort(function(a, b) { return a.x - b.x; });
>     console.timeEnd('sorting');
>
> and it runs in 3.09s under V8 5.3.
>
> I was just wondering, why is it nearly 3x slower under PyPy than it is
> under V8? Is there any way I could make the code run faster?
>
> Thank you in advance!
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>



-- 

Leonardo Santagada
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