Question
RabbitMQ single-node broker (classic queues). At 15:40 producers start reporting blocked publishes and rising publish latency. The broker dashboard shows `mem_used` at 0.95 of `vm_memory_high_watermark`, the node's `connection.blocked` count spiking, and the `orders` queue depth at 2.1M and climbing (messages are not `persistent`; consumers were already lagging). The management UI shows the broker in a memory alarm state. Recent context: the main `orders` consumer group was scaled *down* from 12 to 3 workers in a cost-cutting change yesterday, and inbound order volume is at a normal daily peak. Triage and mitigate before the broker falls over.
Stop the bleeding first (mitigate), then form hypotheses from real signals. Separate root cause from symptom, communicate status as you go, and close with what prevents a repeat.