From time to time on my RoR API service I can see that requests are being interrupted in the middle of processing. Simply the Puma server stops processing the request and right after I can see message in logs saying:

[10] - Worker 0 (PID: 811) booted in 0.01s, phase: 0

I'm trying to figure out what could be the root cause of it. This API service runs in Kubernetes as a pod and in front of this service I have AWS ELB.

Just to be clear, the K8S pod doesn't restart, only one of the Puma's worker gets "killed" and is started again right after.