2019-12-18 web cny error rate spiked up and latency apdex impacted

On December 18th, 2019 - we got several alerts for web-cny stage breaching Latency Apdex threshold and also error rate (PD: https://gitlab.pagerduty.com/incidents/PS0NG4B). Overall slowness within GitLab.com has been observed while navigating and 2 internal users also reported general slowness.

The latest finding that points to the issue symptom is: https://dashboards.gitlab.net/d/HP7LK10Zk/puma-unicorn-on-canary?orgId=1&from=1576628345862&to=1576649945862&var-prometheus=prometheus-01-inf-gprd&var-environment=gprd&var-prometheus_app=prometheus-app-01-inf-gprd&var-node=web-cny-02-sv-gprd.c.gitlab-production.internal&var-node2=web-cny-02-sv-gprd.c.gitlab-production.internal