### Ruby: Demonstrating Event Coalescing with IO::Watch

Source: https://context7.com/socketry/io-watch/llms.txt

This snippet demonstrates how IO::Watch coalesces multiple rapid writes to the same file into a single filesystem event. It sets up a monitor, triggers several writes, and verifies that only one event is received. Dependencies include the 'io/watch' gem and standard Ruby libraries for temporary directories and threads.

```ruby
require 'io/watch'
require 'tmpdir'

Dir.mktmpdir do |root|
  changes = Thread::Queue.new

  thread = Thread.new do
    monitor = IO::Watch::Monitor.new([root])
    monitor.run do |event|
      changes << event
    end
  end

  changes.pop # Wait for start

  test_file = File.join(root, 'test.txt')

  # Multiple rapid writes
  File.write(test_file, 'first')
  File.write(test_file, 'second')
  File.write(test_file, 'third')

  # Only one event is triggered
  event = changes.pop
  puts "Single coalesced event: #{event[:root]}"

  # Queue remains empty despite multiple writes
  sleep 0.5
  if changes.empty?
    puts "No additional events - changes were coalesced"
  end

  thread.kill
end
```

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