Question

I have a question about web farm framework and PLINQ.

As we know, we can use AsParallel extension in .NET 4.0 Framework.

For example

    var source = Enumerable.Range(1, 10000);


// Opt-in to PLINQ with AsParallel
var evenNums = from num in source.AsParallel()
               where Compute(num) > 0
               select num;

I know web farm framework will do the auto load balancing for me.

Assume I have 3 servers:

Sever A: 8 cores
Sever B: 4 cores
Sever C: 4 cores

The question is how many total CPU cores I receive? Is it 8+4+4=16 cores?

I am asking because I am wondering how many CPU cores are available to the parallel computing.

Answer 1

Parallel LINQ is uses the cores available only on the machine it is executing. I believe there are some 3rd party products (Microsoft Research has DryadLINQ) which can extend it to a cluster, however, out of the box this is not possible.

Additionally, cores available and threads used are two separate things (to nitpick even more, unmanaged and managed threads are also two separate things).

To answer your question, regardless of which server the code executes on, PLINQ may use 1 or more threads (up to a limit provided by the scheduler being used). It all depends on the workload.