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Incidents/2022-07-11 FrontendUnavailable cache text

From Wikitech

document status: in-review


Incident metadata (see Incident Scorecard)
Incident ID 2022-07-11 FrontendUnavailable cache text Start 2022-07-11 19:30:00
Task End 2022-07-11 19:36:00
People paged 26 Responder count 5
Coordinators Brandon Black, Arnold Okoth Affected metrics/SLOs No relevant SLOs exist
Impact For 5 minutes, the MediaWiki API cluster in eqiad responded with higher latencies or errors to clients.

There was an increase in requests to the API cluster that resulted in reduction of availabe PHP workers and a database host (db1132) running out of available connections. This database host runs MariaDB 10.6 which is known to be sensitive to high load. This resulted in an increase in latency and errors returned to clients. The spike auto-recovered and it's not clear what the exact root cause was.




Incident Engagement ScoreCard
Question Answer


People Were the people responding to this incident sufficiently different than the previous five incidents? no
Were the people who responded prepared enough to respond effectively yes
Were fewer than five people paged? no
Were pages routed to the correct sub-team(s)? no
Were pages routed to online (business hours) engineers? Answer “no” if engineers were paged after business hours. yes
Process Was the incident status section actively updated during the incident? no
Was the public status page updated? no
Is there a phabricator task for the incident? no
Are the documented action items assigned? yes
Is this incident sufficiently different from earlier incidents so as not to be a repeat occurrence? no
Tooling To the best of your knowledge was the open task queue free of any tasks that would have prevented this incident? Answer “no” if there are

open tasks that would prevent this incident or make mitigation easier if implemented.

Were the people responding able to communicate effectively during the incident with the existing tooling? yes
Did existing monitoring notify the initial responders? yes
Were the engineering tools that were to be used during the incident, available and in service? yes
Were the steps taken to mitigate guided by an existing runbook? no
Total score (count of all “yes” answers above) 7