Skip to content

Enable threaded I/O on redis-cache gprd

Production Change

Change Summary

We are enabling threaded I/O on redis-cache in gprd. This was already done in gstg, see https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/12810.

Change Details

  1. Services Impacted - ServiceRedis
  2. Change Technician - @rehab
  3. Change Reviewer - @igorwwwwwwwwwwwwwwwwwwww
  4. Change Time - 09:30 UTC
  5. Time tracking - 120 minutes
  6. Downtime Component - Reads will remain available, there will be a minimal window of data loss during controlled failover.

Detailed steps for the change

Change Steps - steps to take to execute the change

Estimated Time to Complete (mins) - 105 mins

  • Merge and apply chef change

  • Prepare shell

    cd runbooks

  • Get original config value

    scripts/redis-config-get.sh gprd redis-cache io-threads

    parallel --tag ssh redis-cache-{}-db-gprd.c.gitlab-production.internal sudo gitlab-redis-cli config get io-threads ::: 01 02 03

  • Run reconfigure script

    scripts/redis-reconfigure.sh gprd redis-cache

  • Check that the config value was set

    scripts/redis-config-get.sh gprd redis-cache io-threads

    parallel --tag ssh redis-cache-{}-db-gprd.c.gitlab-production.internal sudo gitlab-redis-cli config get io-threads ::: 01 02 03

Post-Change Steps - steps to take to verify the change

Estimated Time to Complete (mins) - 15 mins

  • Check CPU utilization
    • Dashboard
    • sudo pidstat -t -p $(pidof bin/redis-server) 1
    • (Optional) Record a profile with perf

Rollback

Rollback steps - steps to be taken in the event of a need to rollback this change

Estimated Time to Complete (mins) - 60

  • Revert and apply chef change

  • Prepare shell

    cd runbooks

  • Get original config value

    scripts/redis-config-get.sh gprd redis-cache io-threads

    parallel --tag ssh redis-cache-{}-db-gprd.c.gitlab-production.internal sudo gitlab-redis-cli config get io-threads ::: 01 02 03

  • Run reconfigure script

    scripts/redis-reconfigure.sh gprd redis-cache

  • Check that the config value was set

    scripts/redis-config-get.sh gprd redis-cache io-threads

    parallel --tag ssh redis-cache-{}-db-gprd.c.gitlab-production.internal sudo gitlab-redis-cli config get io-threads ::: 01 02 03

Monitoring

Key metrics to observe

Summary of infrastructure changes

  • Does this change introduce new compute instances?
  • Does this change re-size any existing compute instances?
  • Does this change introduce any additional usage of tooling like Elastic Search, CDNs, Cloudflare, etc?

Summary of the above

Changes checklist

  • This issue has a criticality label (e.g. C1, C2, C3, C4) and a change-type label (e.g. changeunscheduled, changescheduled) based on the Change Management Criticalities.
  • This issue has the change technician as the assignee.
  • Pre-Change, Change, Post-Change, and Rollback steps and have been filled out and reviewed.
  • Necessary approvals have been completed based on the Change Management Workflow.
  • Change has been tested in staging and results noted in a comment on this issue.
  • A dry-run has been conducted and results noted in a comment on this issue.
  • SRE on-call has been informed prior to change being rolled out. (In #production channel, mention @sre-oncall and this issue and await their acknowledgement.)
  • Release managers have been informed (If needed! Cases include DB change) prior to change being rolled out. (In #production channel, mention @release-managers and this issue and await their acknowledgment.)
  • There are currently no active incidents.
Edited by Rehab