[Twisted-Python] Twisted slow in Mac OS X fast on Windows

[Brian Granger]

Hi,

I think it may just be the built-in Python on Leopard:

On OS X:

In [1]: def f():
   ...:     for i in range(100000):
   ...:         a = 1 + i
In [2]: %timeit f()
100 loops, best of 3: 11.8 ms per loop

Same hardware, but Windows:

In [1]: def f():
   ...:     for i in range(100000):
   ...:         a = 1 + i
In [2]: %timeit f()
100 loops, best of 3: 8.33 ms per loop

That's depressing...

Cheers,

Brian


On Fri, Feb 20, 2009 at 11:19 AM, Jean-Paul Calderone
<exarkun at divmod.com> wrote:
> On Fri, 20 Feb 2009 11:11:24 -0800, Brian Granger <ellisonbg.net at gmail.com>
> wrote:
>>
>> Hi,
>>
>> We use Twisted extensively in the IPython project for parallel and
>> distributed computing.  We have an extensive test suite that uses
>> trial to test our servers and clients.  Everything works
>> great...but...the test suite takes much longer to run on OS X than
>> windows.  Here is what I mean:
>>
>> 1.  2.53 Ghz Intel Core 2 Duo, Mac OS X 10.5.  Test suite takes 67 seconds
>>
>> 2.  *Same machine*, running Windows XP as VM in VMWare.  Test suite
>> takes 17 seconds.
>>
>> I have verified that all the tests are being run on Windows.  This is
>> very surprising to me as I would expect, if anything, the Windows VM
>> to be a bit slower, not 3x faster.  This is the same hardware, the
>> same code, the only thing that I can think of that is different is the
>> reactor implementation.  I am using the default reactor on both
>> platforms.
>>
>> Questions:
>>
>> * Is the Windows reactor really that fast?
>
> Probably not.  But it depends what your test suite does.
>
>> * Is the default (I think it is select) reactor on OS X really that slow?
>
> Probably not.  But it depends what your test suite does.
>
>> * Why else would it be that slow on OS X?
>> * What can I do to speed this up?
>
> The only thing that comes to mind is that some hostname lookup functions
> used to be pretty slow on OS X.  I have no idea if this is still the case.
> I suggest profiling the suite on OS X and Windows and comparing the results
> to get a better idea of where to look for the problem.
>
> Jean-Paul
>
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