pi_mc_multi_threaded.jl

using BenchmarkTools, StaticArrays, Transducers

function _pi_kernel_static()
    xs = @SVector rand(50)
    ys = @SVector rand(50)
    sum(((x, y),) -> x^2 + y^2 < 1.0, zip(xs, ys))
end
function _pi_kernel(r)
    xs = rand(r)
    ys = rand(r)
    sum(((x, y),) -> x^2 + y^2 < 1.0, zip(xs, ys))
end

function pi_mc(nsamples)
    acc = 0
    n, remainder = divrem(nsamples, 50)
    acc += reduce(+, Map(_ -> _pi_kernel_static()), 1:n) 
    if remainder != 0
        acc += _pi_kernel(remainder)
    end
    return 4acc/nsamples
end

@benchmark pi_mc(x) setup=(x=10_000_000) 
#= On a Ryzen 5 2600 using 6 threads, I get 
BenchmarkTools.Trial:
  memory estimate:  16.56 KiB
  allocs estimate:  313
  --------------
  minimum time:     10.754 ms (0.00% GC)
  median time:      10.993 ms (0.00% GC)
  mean time:        11.039 ms (0.00% GC)
  maximum time:     14.221 ms (0.00% GC)
  --------------
  samples:          453
  evals/sample:     1
=#