[Haskell-cafe] Haskell vs. Erlang for heavy-duty network apps (was
Re: Haskell Speed)
joelr1 at gmail.com
Sun Dec 25 07:20:38 EST 2005
On Dec 25, 2005, at 10:13 AM, Bulat Ziganshin wrote:
> Hello Joel,
> so i think that your problems is due to bad design decisions caused by
> lack of experience. two weeks ago when you skipped my suggestions
> about improving this design and answered that you will use "systematic
> approach", i foresee that you will fail and say that Haskell is a bad
Yes and no. The systematic approach that I used was profiling the
serialization code and tweaking all that I could. I saved my
profiling reports after each run and tracked the changes that I made.
I will blog about it after Simon M. comes back and suggests how to
squeeze the last bit out of it.
Regardless of this, it looks to me like I could easily have around
4Mb of network traffic per second with about 4k threads and
complicated nested structures to serialize and deserialize. Trying to
tackle far less data suggests to me that it's not gonna happen. So I
will try to take this as far as I can in Haskell, once I have the
heavy artillery to back me up. If the results are good then I will
use them in later applications of the same nature but in the meantime
I'm rewriting this particular app in Erlang.
There are other apps to write in Haskell but my overall lesson is
that the choice of right tool for the task at hand will help far more
than any optimizations you can produce. Specially when the natural
approach to the problem will just produce the results required.
I spent 3 months with this app, going from total Haskell newbie who
has not seen Haskell before to someone who can read Haskell core code
and tackle FFI and networking in a heavily concurrent environment. I
still don't know what "the right thing" is.
The Erlang rewrite should take me 2-3 days with FFI being the teeth-
grinding bit. I need the FFI (which totally sucks compared to
Haskell's) because my use of SSL and ZLib is non-standard, otherwise
these are already provided to you. I expect that the app will just
work. No memory or time leaks. The serialization approach that I'm
using is based on the pickler combinators but slightly different. I
think I'll backport it to Haskell to compare.
The next project on my plate is real-time collusion detection in
poker. I first thought of using the Dazzle approach and Bayesian
networks but the focus again seems to be on high-throughput
networking and scalability. What language will I use? Haskell is no
A disclaimer for those who might think that I'm a newbit
disillutioned with Haskell... I totally love Haskell, it just seems
that you need to be a guru to do what I'm trying to do and I have not
yet reached this status. I will not rest until I'm able to see just
_what_ kind of a performance can be squeezed from Haskell for my
application. I'll also continue to seek enlightenment but I need to
finish this project before New Year's.
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