Re: RFC: Prototype for a user threading library in Ada

[rieachus@comcast.net]

On Friday, June 17, 2016 at 12:46:46 PM UTC-4, Dmitry A. Kazakov wrote:
> On 2016-06-17 18:18, Niklas Holsti wrote:
> 
> My take on this problematic is that there cannot exist a solution 
> implemented at the library level. All these frameworks maybe fun (for 
> the developer) but useless (horror for the end user) when the key 
> problem is not solved. That is, the control-flow state (as you said) and 
> the stack of the local objects both preserved between scheduling points. 
> This can be done IMO only at the language level as co-routines, 
> non-preemptive, cooperative, user-scheduled tasks, call it as you wish.

I've been trying to understand not just the code, but the goal.  I decided to start from a different perspective.  What if I had a problem and wanted to distribute the solution across thousands of processors?  Since I tend to bang my head against NP-hard or NP-complete problems, I would want a program structure that allowed me to start up at least one (Ada) task per processor, with enough data to complete, and for the job creation software to use a very wide tree.  A similar reverse tree could be used to collect results if needed.

But to do any of this, I head for the distributed systems annex.  It might be nice to have a simple example of how to do that on top of MPI:  https://computing.llnl.gov/tutorials/mpi/#MPI2-3 (To be honest, using the C or Fortran bindings is what I have done...)