open3 async test

open3_demo.rb

require 'open3'
require 'benchmark'

Thread.abort_on_exception = true

lamb = lambda do |input, out, _thread|
  output_thread = Thread.new do
    log 'output thread started'
    out.each_line do |line|
      log line.strip
    end
  end

  log 'sending data to stdin'
  10.times do |i|
    sleep 0.1
    input.puts "i => #{i}"
  end
  input.close

  log 'joining output thread'
  log Benchmark.measure { output_thread.join }
  log 'done'
end

def log(text)
  puts "[#{Thread.current.object_id}] #{text}"
end

# `cat` handles streaming correctly
log 'Running `cat`...'
Open3.popen2('cat', &lamb)

puts
log 'Running `sed`...'
# `sed` waits for end of input :/
Open3.popen2('sed', '-e', 's/i/eye/', &lamb)

Uploaded to repl.it: https://repl.it/JpHZ/0