Example Ruby M:N threading

mxn.rb

M = 4

Result = Data.define(:idx, :val)

def gather(funcs)
  ready = Queue.new
  funcs.each_with_index {|val,idx| ready << Result.new(val:, idx:) }
  result = []
  (0..M).map do
    Thread.new do
      begin
        while job = ready.pop(true)
          result[job.idx] = job.val.()
        end
      rescue ThreadError
        # queue empty
      end
    end
  end.map(&:join).map(&:value).flatten
  result
end

funcs = (1..10).map {|i|
  -> { "Value #{i}" }
}

p gather(funcs)