[Haskell-cafe] safe lazy IO or Iteratee?

[John Lato]

On Fri, Feb 5, 2010 at 4:31 PM, Valery V. Vorotyntsev
<valery.vv at gmail.com> wrote:
>> John Lato <jwlato at gmail.com> wrote:
>>
>>> Both designs appear to offer similar performance in aggregate,
>>> although there are differences for particular functions.  I haven't
>>> yet had a chance to test the performance of the CPS variant, although
>>> Oleg has indicated he expects it will be higher.
>
> @jwlato:
> Do you mind creating `IterateeCPS' tree in
> <http://inmachina.net/~jwlato/haskell/iteratee/src/Data/>, so we can
> start writing CPS performance testing code?

I'm working on the CPS version and will make it public when it's done.
 It may take a week or so; this term started at 90 and has picked up.
I have several benchmark sources that aren't public yet, but I can put
them online for your perusal.

>
> AFAICS, you have benchmarks for IterateeM-driven code already:
> http://inmachina.net/~jwlato/haskell/iteratee/tests/benchmarks.hs

Those will make more sense when I've added the context of the
codebases in use.  There are several more sets of output that I simply
haven't published yet, including bytestring-based variants.

>
> John Millikin <jmillikin at gmail.com> wrote:
>
>> I wrote some criterion benchmarks for IterateeM vs IterateeCPS, and
>> the CPS version was notably slower. I don't understand enough about
>> CPS to diagnose why, but the additional runtime was present in even
>> simple cases (reading from a file, writing back out).

That's very interesting.  I wonder if I'll see the same, and if I'd be
able to figure it out myself...

Did you benchmark any cases without doing IO?  Sometimes the cost of
the IO can overwhelm any other measurable differences, and also disk
caching can affect results.  Criterion should highlight any major
outliers, but I still like to avoid IO when benchmarking unless
strictly necessary.

>
> @jmillikin:
> Could you please publish those benchmarks?

+1

John