CR [GPRD] test increased work_mem on one node
Production Change
Change Summary
In line with Increase work_mem for gitlab.com main database this tests a higher value for work_mem
on a single cluster node.
The expectation is to reduce the amount of temp data spilled to disk. This change should persist for +1 week to gather enough data to decide if it is rolled back or persisted across the fleet.
Change Details
- Services Impacted - ServicePatroni
- Change Technician - @alexander-sosna
- Change Reviewer - TBA
- Time tracking - < 90 minutes
- Downtime Component - No downtime
Set Maintenance Mode in GitLab
If your change involves scheduled maintenance, add a step to set and unset maintenance mode per our runbooks. This will make sure SLA calculations adjust for the maintenance period.
Detailed steps for the change
Change Steps - steps to take to execute the change
Estimated Time to Complete (mins) - 70
-
Set label changein-progress /label ~change::in-progress
-
Check which node is Leader
and which havenoloadbalance
set,knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "sudo gitlab-patronictl list"
-
Verify patroni-main-v14-08-db-gprd
has setnofailover: true
-
Verify current work_mem
is100MB
,knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "gitlab-psql --csv -t -c 'SHOW work_mem;'"
-
Set work_mem
to230MB
,knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "gitlab-psql --csv -t -c 'ALTER SYSTEM SET work_mem = '230MB';'"
-
Reload configuration , knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "gitlab-psql --csv -t -c 'SELECT pg_reload_conf();'"
-
Verify current work_mem
is230MB
now,knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "gitlab-psql --csv -t -c 'SHOW work_mem;'"
-
Monitor the metrics closely for 1h. -
Set label changecomplete /label ~change::complete
Rollback
Rollback steps - steps to be taken in the event of a need to rollback this change
Estimated Time to Complete (mins) - 10
-
Reset work_mem
to default100MB
,knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "gitlab-psql --csv -t -c 'ALTER SYSTEM RESET work_mem;'"
-
Reload configuration , knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "gitlab-psql --csv -t -c 'SELECT pg_reload_conf();'"
-
Verify current work_mem
is100MB
again,knife ssh 'patroni-main-v14-08-db-gprd.c.gitlab-production.internal' "gitlab-psql --csv -t -c 'SHOW work_mem;'"
-
Set label changeaborted /label ~change::aborted
Monitoring
Key metrics to observe
A rollback here is an easy and cheap operation, when in doubt, rollback!
-
Metric: Apdex
- Location: https://dashboards.gitlab.net/d/patroni-main/patroni3a-overview?orgId=1
- What changes to this metric should prompt a rollback: Degradation.
-
Metric: Memory saturation on
patroni-main-v14-08-db-gprd.c.gitlab-production.internal
- Location: https://dashboards.gitlab.net/d/patroni-main/patroni3a-overview?orgId=1&viewPanel=79
- What changes to this metric should prompt a rollback: Degradation.
Change Reviewer checklist
-
Check if the following applies: - The scheduled day and time of execution of the change is appropriate.
- The change plan is technically accurate.
- The change plan includes estimated timing values based on previous testing.
- The change plan includes a viable rollback plan.
- The specified metrics/monitoring dashboards provide sufficient visibility for the change.
-
Check if the following applies: - The complexity of the plan is appropriate for the corresponding risk of the change. (i.e. the plan contains clear details).
- The change plan includes success measures for all steps/milestones during the execution.
- The change adequately minimizes risk within the environment/service.
- The performance implications of executing the change are well-understood and documented.
- The specified metrics/monitoring dashboards provide sufficient visibility for the change.
- If not, is it possible (or necessary) to make changes to observability platforms for added visibility?
- The change has a primary and secondary SRE with knowledge of the details available during the change window.
- The change window has been agreed with Release Managers in advance of the change. If the change is planned for APAC hours, this issue has an agreed pre-change approval.
- The labels blocks deployments and/or blocks feature-flags are applied as necessary.
Change Technician checklist
-
Check if all items below are complete: - The change plan is technically accurate.
- This Change Issue is linked to the appropriate Issue and/or Epic
- 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.
- The change execution window respects the Production Change Lock periods.
- For C1 and C2 change issues, the change event is added to the GitLab Production calendar.
- For C1 and C2 change issues, the 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.) - For C1 and C2 change issues, the SRE on-call provided approval with the eoc_approved label on the issue.
- For C1 and C2 change issues, the Infrastructure Manager provided approval with the manager_approved label on the issue.
- Release managers have been informed prior to any C1, C2, or blocks deployments change being rolled out. (In #production channel, mention
@release-managers
and this issue and await their acknowledgment.) - There are currently no active incidents that are severity1 or severity2
- If the change involves doing maintenance on a database host, an appropriate silence targeting the host(s) should be added for the duration of the change.