Unbounded heap growth when consumer pool can't handle the load

[leksito]

If the number of incoming messages is greater than the consumer is handling, the memory usage increases infinitely over time.
The simplest ruby ​​script can use a huge amount of memory

require 'bunny'

Process.setproctitle("test_consumer")

conn = Bunny.new(
# bunny conf
)
conn.start
channel = conn.create_channel

exchange = channel.send(:fanout, 'test')
queue = channel.queue('test_queue', exclusive: false)
queue.bind(exchange)

queue.subscribe do |*args|
  puts args.inspect[0..100]
  sleep 0.01 # mock message handling
end

Thread.list.reject { |t| t == Thread.current }.each(&:join)

and this memory is not released even after reducing the load

[leksito]

#604

[michaelklishin]

This is expected. Consumers should use manual acknowledgements with a low enough prefetch value on their channels. This is the only fundamental solution.