Ruby 4.0 Ractor push type (send/receive) communication with Ractor::Port

example.rb

# frozen_string_literal: true

p RACTOR_COUNT: Ractor.count # => 1
p IS_MAIN_RACTOR: Ractor.main? # => true
p Ractor.main  # => #<Ractor:#1 running>

port = Ractor::Port.new
p port # => #<Ractor::Port to:#1 id:1>
Ractor.new(port) do |port|
  p RACTOR_COUNT: Ractor.count # => 2
  p IS_MAIN_RACTOR: Ractor.main? # => false
  p RACTOR: Ractor.current # => #<Ractor:#2 ractor_port.rb:9 running>
  p PORT: port # => #<Ractor::Port to:#1 id:1>
  p DEFAULT_PORT: Ractor.current.default_port # => #<Ractor::Port to:#2 id:0>
  p "Sending to port #{port}"
  port.send 42
end

p PRE_RECEIVE_RACTOR_COUNT: Ractor.count # => 2
p "Receiving from port #{port}"
p port.receive

p FINAL_RACTOR_COUNT: Ractor.count # => 1

• https://www.ruby-lang.org/en/news/2025/12/25/ruby-4-0-0-released/#ractor-improvements
• https://docs.ruby-lang.org/en/4.0/Ractor.html

$ ruby example.rb
{RACTOR_COUNT: 1}
{IS_MAIN_RACTOR: true}
#<Ractor:#1 running>
#<Ractor::Port to:#1 id:1>
ractor_port.rb:9: warning: Ractor API is experimental and may change in future versions of Ruby.
{PRE_RECEIVE_RACTOR_COUNT: 2}
"Receiving from port #<Ractor::Port:0x0000000123186838>"
{RACTOR_COUNT: 2}
{IS_MAIN_RACTOR: false}
{RACTOR: #<Ractor:#2 example.rb:9 running>}
{PORT: #<Ractor::Port to:#1 id:1>}
{DEFAULT_PORT: #<Ractor::Port to:#2 id:0>}
"Sending to port #<Ractor::Port:0x0000000123186838>"
42
{FINAL_RACTOR_COUNT: 1}