2022-09-17: Patroni CI statement timeouts and elevated CI job error rate
Incident Roles
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Roles when the incident was declared:
Current Status
A single specific SQL query abruptly started timing out in the primary CI database. This query is run by 2 endpoints:
- HTTP
POST
requests to API endpoint/api/v4/jobs/:id/artifacts
. -
Ci::ArchiveTraceWorker
- A worker that moves CI job trace output between storage tiers. No user-facing impact. Failed attempts should get retried.
So far it looks like the query regression is likely due to a plan mutation in combination with a competing workload. The relevant optimizer statistics used by the query planner were updated near the start of the regression, but they have not been updated again since the end of the regression. It looks like only certain combinations of filter values are likely to trigger this behavior. This may limit the scope of impact to only a small subset of projects.
Query analysis starts here: #7756 (comment 1104362118)
Conclusions: #7756 (comment 1104371432)
More information will be added as we investigate the issue. For customers believed to be affected by this incident, please subscribe to this issue or monitor our status page for further updates.
Summary for CMOC notice / Exec summary:
- Customer Impact: Some CI-related API calls failed due to query timeouts. The archiving of some CI job trace output was also delayed, but that should not have caused user-facing impact, since those job traces were still available in Redis.
- Service Impact: ServiceCI Runners and ServicePatroniCI
- Impact Duration: 2022-09-17 21:17 - 21:28 UTC (11 minutes)
- Root cause: TBD
Timeline
Recent Events (available internally only):
- Deployments
- Feature Flag Changes
- Infrastructure Configurations
- GCP Events (e.g. host failure)
- Gitlab.com Latest Updates
All times UTC.
2022-09-17
-
21:33
- @msmiley declares incident in Slack.
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