client.cr

require "socket"
require "benchmark"

socket = TCPSocket.new "localhost", 8081

# socket.tcp_nodelay = true
# socket.sync = true

data = Bytes.new 20

Benchmark.ips do |x|
  x.report("ping") do
    socket.write data
    socket.read_fully data
  end
end

server.cr

require "socket"

server = TCPServer.new "localhost", 8081

buf = Bytes.new 20
while socket = server.accept
#   socket.tcp_nodelay = true
#   socket.sync = true

  spawn do
    begin
      loop do
        socket.read_fully buf

        spawn do
          socket.write buf
        end
      end
    ensure
      socket.close
    end
  end
end