Noisy Neighbor - CI/CD Glossary Definition

A noisy neighbor is a workload sharing a machine that consumes a disproportionate amount of a shared resource (CPU, memory bandwidth, disk I/O, or network) and degrades the performance of co-located workloads. On densely packed CI runners it causes intermittent, hard-to-reproduce slowdowns.

Symptoms in CI

A job that usually finishes in 4 minutes occasionally takes 12 with no code change, because another job on the same host saturated disk I/O or memory bandwidth. Because the cause lives outside your job, it reads as flakiness. Ephemeral, single-job runners eliminate noisy neighbors by giving each job its own machine.

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