Rabbitmq one queue multiple consumers

Question

I've multiple consumers which are polling on the same queue, and checking the queue every X seconds, basically after X seconds it could be that at least two consumers can launch basic.get at the very same time.

Question are:
1.If at least two consumers at the same time can get the same message?

2.According to what I understood only basic_ack will delete a mesage from the queue, so suppose we have the following scenario:

Consumer1 takes msg with basic.get and before it reaches basic_ack line , Consumer2 is getting this message also ( basic.get ), now Consumer1 reaches the basic.ack , and only now Consumer2 reaches its own basic.ack .
What will happen When Consumer2 will reach its basic.ack ?
Will the message be processes by Consumer2 as well, because actions are not atomic?

My code logic of consumer using python pika is as follows:

while true: m_frame =None while(m_frame is None):
self.connection.sleep(10) m_frame,h_frame,body = self.channel.basic_get('test_queue') self.channel.basic_ack(m_frame.delivery_tag) [Doing some long logic - couple of minutes]

Please note that I don't use basic.consume

So I don't know if round robin fetching is included for such usage

Answer 1

1.If at least two consumers at the same time can get the same message?

no - a single message will only be delivered to a single consumer.

Because of that, your scenario #2 doesn't come into play at all.

You'll never have 2 consumers working on the same message, unless you nack the message back to the queue but continue processing it anyways.