Thanks for the reply! I don't think a reverse counter is better because TimSort (used in PyPy?) is able to recognise the pattern [1] and do better than other kinds of sorts. And almost for a year [2] now, V8 implements random as XorShift128+ which very good. I also tried different sizes and the timings still show similar difference.
[1] http://c2.com/cgi/wiki?TimSort [2] https://bugs.chromium.org/p/chromium/issues/detail?id=559024 On Mon, Oct 3, 2016 at 10:46 AM, Leonardo Santagada <santag...@gmail.com> wrote: > 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.lar...@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! >> _______________________________________________ >> pypy-dev mailing list >> pypy-dev@python.org >> https://mail.python.org/mailman/listinfo/pypy-dev > > > > > -- > > Leonardo Santagada _______________________________________________ pypy-dev mailing list pypy-dev@python.org https://mail.python.org/mailman/listinfo/pypy-dev
