CPU consumption while using Task.Run vs Background thread

[bmwhite20]

Hi David,

Hope you are doing well!

Following your (awesome) async guidance, I'm having a strange behavior while testing a long-running message consumer with Task.Run vs Background Thread.

Code sample:

        public async Task MainAsync(string[] args)
        {
            var backgroundThread = new Thread(Consume)
            {
                IsBackground = true
            };

            backgroundThread.Start(); //CPU - NOK

            await Task.Run(Consume); //CPU - OK
        }

        private void Consume()
        {
            //while loop (sync) consuming messages from Kafka
        }

Test conditions:

• K8s cluster
• 3 pods
• Kafka cluster
• 3 partitions by topic

Background thread

Task.Run

As we can see, pods running with background thread are struggling the CPU.

Do you have any thoughts why it happens?

Code: https://github.com/bmwhite20/cpu-workload

Best, Bruno

[newbe36524]

As I understand it, it is a matter of Kafka's own implementation. If you want to understand the CPU difference between the two ways of writing code. Then Kafka should not be introduced.

As for Kafka itself, it is actually recommended to use Consume with Timeout, and I think this case may be related to your question. https://github.com/confluentinc/confluent-kafka-dotnet/issues/1261

[bmwhite20]

It's definitely related with Kafka