2020-12-03: Gitaly latency drop on canary

Summary

We see several latency spikes for gitaly on canary correlated with CPU saturation, which is caused by dramatically increased PostUploadPack request times for the gitlab-org/gitlab repo.

Timeline

All times UTC.

2020-12-03

• 11:30 - gitaly latency starting to grow
• 11:42 - gitlay CPU utilization alert
• 12:00 - latency down again
• 12:05 - 2nd wave starting
• 12:15 - hphilipps declares incident in Slack.
• 12:25 - 2nd wave over
• 13:00 - 3rd wave starting
• 13:20 - 3rd wave over

Corrective Actions

Click to expand or collapse the Incident Review section.

Incident Review

Summary

1. Service(s) affected:
2. Team attribution:
3. Time to detection:
4. Minutes downtime or degradation:

Metrics

Customer Impact

1. Who was impacted by this incident? (i.e. external customers, internal customers)
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2. What was the customer experience during the incident? (i.e. preventing them from doing X, incorrect display of Y, ...)
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3. How many customers were affected?
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4. If a precise customer impact number is unknown, what is the estimated impact (number and ratio of failed requests, amount of traffic drop, ...)?
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What were the root causes?

("5 Whys")

Incident Response Analysis

1. How was the incident detected?
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2. How could detection time be improved?
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3. How was the root cause diagnosed?
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4. How could time to diagnosis be improved?
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5. How did we reach the point where we knew how to mitigate the impact?
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6. How could time to mitigation be improved?
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7. What went well?
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Post Incident Analysis

1. Did we have other events in the past with the same root cause?
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2. Do we have existing backlog items that would've prevented or greatly reduced the impact of this incident?
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3. Was this incident triggered by a change (deployment of code or change to infrastructure)? If yes, link the issue.
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Lessons Learned

Guidelines

• Blameless RCA Guideline