Why does Redpanda consume so much CPU?

 

This is an expected behavior of the Redpanda Architecture.

While CPU utilization at the host-level might appear high (for example, 99-100% utilization) when I/O events like message arrival occur, the actual Redpanda process utilization is likely low. System-level metrics such as those provided by the top command can be misleading.

This high host-level CPU utilization happens because Redpanda uses Seastar, which runs event loops on every core (also referred to as a reactor), constantly polling for the next task. This process never blocks and will increment clock ticks. It doesn’t necessarily mean that Redpanda is busy.

Use redpanda_cpu_busy_seconds_total (public metrics) or vectorized_reactor_utilization (internal metrics) to monitor the actual Redpanda CPU utilization. When these particular metrics indicate close to 100% utilization over a given period of time, make sure to also monitor produce and consume latency as they may then start to increase as a result of resources becoming overburdened.

If you have further questions please reach out to Redpanda Support.