EnvoyEnvoy ProxyIstio

High-cardinality metric labels cause stats explosion and memory growth

warning
performanceUpdated Feb 24, 2026(via Exa)
Sources
How to Diagnose Envoy Proxy High Memory Usage in Istiooneuptime.com
Technologies:
Envoysubject
Envoy ProxySymptoms of this issue are visible in Envoy Proxy metrics and logs
IstioThe root cause of this issue originates in Istio
How to detect:

Each unique metric label combination consumes memory. High-cardinality labels like per-path metrics or per-user-ID labels cause stats to explode to tens of thousands, consuming significant memory.

Recommended action:

Count total stats with pilot-agent. If tens of thousands, apply Telemetry resource with tagOverrides to REMOVE high-cardinality labels like destination_canonical_revision, source_canonical_revision, and request_protocol.