TCP server with Thread per connection

Three lines of substance: TCPServer.new opens the port. accept loops. Thread.new spawns one MRI thread per connection. Done.

01-tcp-echo/server.rb

ruby

require 'socket'

server = TCPServer.new('127.0.0.1', 6380)
loop do
  client = server.accept
  Thread.new(client) do |conn|
    begin
      while (data = conn.recv(4096)) && !data.empty?
        conn.write(data)
      end
    rescue IOError, Errno::ECONNRESET
    ensure
      conn.close rescue nil
    end
  end
end

The entire echo server. The GIL serialises bytecode but releases on recv, so threads cooperate.

The GIL serialises Ruby bytecode execution, but it releases during blocking IO (recv, write, sleep). For a network server, that means threads effectively cooperate: one is waiting on IO, another runs bytecode. CPU-bound work would hit the GIL ceiling; IO-bound work does not.

Quiz: Quiz

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