[erlang-questions] Erlang on supercomputers

[Mats Cronqvist]

Chad Brewbaker wrote:
> The problems with Bluegene/L are:
> 
> 1. The compute node kernel only allows user process per CPU. I haven't
> looked into the Erlang source much, but all threading must be "green".

   i believe the emulator threading can be turned off at run-time (afaik even 
the non-SMP emu (optionally) uses threads for io).

> 2. Communication is done over MPI in C/C++/Fortran. There is no API for
> doing TCP/IP communication I know of, but if you are feeling lucky you can
> use un-documented low level communication API's.

   it is possible (and supposedly not very hard) to implement the erlang 
distribution over a different carrier than the default TCP/IP. documented in the 
ERTS manual.

> 3. You need to cross compile, so all cross compilation problems with Erlang
> apply.

   several people on the mailing list claims to cross-compile without major 
problems. see also the FAQ :>  http://erlang.org/faq/x867.html#AEN963

> I just got Ruby working on Bluegene/L and was thinking about doing Erlang
> next:
> http://www.ece.iastate.edu/~crb002/cnr.html
> 
> I don't know if I am a fan of Erlang yet or not. I'm on the fence weather I
> should try porting it or just implement Erlang message passing 
> functionality
> I want as a Ruby library.

   not that i know anything about supercomputers or ruby, but i would bet real 
money that in a cluster of 2048 cpu's erlang would beat the pants off ruby. 
erlang is typically faster than ruby, and generally performs very well in a 
distributed environment.

   mats