Performance degradation archiving DB with large numbers of FK related records
| Affects | Status | Importance | Assigned to | Milestone | |
|---|---|---|---|---|---|
| OpenStack Compute (nova) |
Fix Released
|
Undecided
|
melanie witt | ||
| Antelope |
In Progress
|
Undecided
|
Unassigned | ||
| Wallaby |
In Progress
|
Undecided
|
Unassigned | ||
| Xena |
In Progress
|
Undecided
|
Unassigned | ||
| Yoga |
In Progress
|
Undecided
|
Unassigned | ||
| Zed |
In Progress
|
Undecided
|
Unassigned | ||
| nova (Ubuntu) |
Won't Fix
|
Undecided
|
Unassigned | ||
| Focal |
Fix Committed
|
Undecided
|
Chengen Du | ||
| Jammy |
Fix Committed
|
Undecided
|
Chengen Du | ||
Bug Description
[Impact]
Originally, Nova archives deleted rows in batches consisting of a maximum number of parent rows (max_rows) plus their child rows, all within a single database transaction.
This approach limits the maximum value of max_rows that can be specified by the caller due to the potential size of the database transaction it could generate.
Additionally, this behavior can cause the cleanup process to frequently encounter the following error:
oslo_db.
The error arises when the transaction exceeds the group replication transaction size limit, a safeguard implemented to prevent potential MySQL crashes [1].
The default value for this limit is approximately 143MB.
[Fix]
An upstream commit has changed the logic to archive one parent row and its related child rows in a single database transaction.
This change allows operators to choose more predictable values for max_rows and achieve more progress with each invocation of archive_
Additionally, this commit reduces the chances of encountering the issue where the transaction size exceeds the group replication transaction size limit.
commit 697fa3c000696da
Author: melanie witt <email address hidden>
CommitDate: Tue Jun 20 20:04:46 2023 +0000
database: Archive parent and child rows "trees" one at a time
[Test Plan]
1. Create an instance and delete it in OpenStack.
2. Log in to the Nova database and confirm that there is an entry with a deleted_at value that is not NULL.
select display_name, deleted_at from instances where deleted_at <> 0;
3. Execute the following command, ensuring that the timestamp specified in --before is later than the deleted_at value:
nova-manage db archive_
4. Log in to the Nova database again and confirm that the entry has been archived and removed.
select display_name, deleted_at from instances where deleted_at <> 0;
[Where problems could occur]
The commit changes the logic for archiving deleted entries to reduce the size of transactions generated during the operation.
If the patch contains errors, it will only impact the archiving of deleted entries and will not affect other functionalities.
[1] https:/
[Original Bug Description]
Observed downstream in a large scale cluster with constant create/delete
server activity and hundreds of thousands of deleted instances rows.
Currently, we archive deleted rows in batches of max_rows parents +
their child rows in a single database transaction. Doing it that way
limits how high a value of max_rows can be specified by the caller
because of the size of the database transaction it could generate.
For example, in a large scale deployment with hundreds of thousands of
deleted rows and constant server creation and deletion activity, a
value of max_rows=1000 might exceed the database's configured maximum
packet size or timeout due to a database deadlock, forcing the operator
to use a much lower max_rows value like 100 or 50.
And when the operator has e.g. 500,000 deleted instances rows (and
millions of deleted rows total) they are trying to archive, being
forced to use a max_rows value several orders of magnitude lower than
the number of rows they need to archive is a poor user experience and
makes it unclear if archive progress is actually being made.
| description: | updated |
| Changed in nova: | |
| status: | New → In Progress |
| OpenStack Infra (hudson-openstack) wrote Fix included in openstack/nova 28.0.0.0rc1 | #1 |
| melanie witt (melwitt) wrote | #2 |
| Changed in nova: | |
| status: | In Progress → Fix Released |
| melanie witt (melwitt) wrote | #3 |
| melanie witt (melwitt) wrote | #4 |
| melanie witt (melwitt) wrote | #5 |
| melanie witt (melwitt) wrote | #6 |
| melanie witt (melwitt) wrote | #7 |
| OpenStack Infra (hudson-openstack) wrote Change abandoned on nova (stable/yoga) | #8 |
| OpenStack Infra (hudson-openstack) wrote Change abandoned on nova (stable/ussuri) | #9 |
| OpenStack Infra (hudson-openstack) wrote Change abandoned on nova (stable/victoria) | #10 |
| OpenStack Infra (hudson-openstack) wrote Change abandoned on nova (stable/wallaby) | #11 |
| OpenStack Infra (hudson-openstack) wrote Change abandoned on nova (stable/xena) | #12 |
| OpenStack Infra (hudson-openstack) wrote Change abandoned on nova (stable/zed) | #13 |
| Chengen Du (chengendu) wrote | #15 |
| Changed in nova (Ubuntu Focal): | |
| status: | New → In Progress |
| Changed in nova (Ubuntu Jammy): | |
| status: | New → In Progress |
| Changed in nova (Ubuntu Focal): | |
| assignee: | nobody → Chengen Du (chengendu) |
| Changed in nova (Ubuntu Jammy): | |
| assignee: | nobody → Chengen Du (chengendu) |
| Ubuntu Foundations Team Bug Bot (crichton) wrote | #16 |
| tags: | added: patch |
| description: | updated |
| Steve Langasek (vorlon) wrote | #17 |
| Changed in nova (Ubuntu): | |
| status: | New → Incomplete |
| Chengen Du (chengendu) wrote | #18 |
| Changed in nova (Ubuntu): | |
| status: | Incomplete → Won't Fix |
| Lukas Märdian (slyon) wrote | #19 |
| Lukas Märdian (slyon) wrote | #20 |
| Mauricio Faria de Oliveira (mfo) wrote | #21 |
| Lukas Märdian (slyon) wrote | #22 |
| Mauricio Faria de Oliveira (mfo) wrote | #23 |
| Mauricio Faria de Oliveira (mfo) wrote | #24 |
| Andreas Hasenack (ahasenack) wrote Please test proposed package | #25 |
| Changed in nova (Ubuntu Jammy): | |
| status: | In Progress → Fix Committed |
| tags: | added: verification-needed verification-needed-jammy |
| Changed in nova (Ubuntu Focal): | |
| status: | In Progress → Fix Committed |
| tags: | added: verification-needed-focal |
| Andreas Hasenack (ahasenack) wrote | #26 |
| Ubuntu SRU Bot (ubuntu-sru-bot) wrote Autopkgtest regression report (nova/2:21.2.4-0ubuntu2.12) | #27 |
| Chengen Du (chengendu) wrote | #28 |
| tags: |
added: verification-done-jammy removed: verification-needed-jammy |
| Chengen Du (chengendu) wrote | #29 |
| tags: |
added: verification-failed-focal removed: verification-needed verification-needed-focal |
| Mauricio Faria de Oliveira (mfo) wrote | #30 |
| Mauricio Faria de Oliveira (mfo) wrote | #31 |
| Mauricio Faria de Oliveira (mfo) wrote | #32 |
| Andreas Hasenack (ahasenack) wrote Please test proposed package | #33 |
| tags: |
added: verification-needed verification-needed-focal removed: verification-failed-focal |
| Ubuntu SRU Bot (ubuntu-sru-bot) wrote Autopkgtest regression report (nova/2:21.2.4-0ubuntu2.13) | #34 |
| Chengen Du (chengendu) wrote | #35 |
| tags: |
added: verification-done-focal removed: verification-needed verification-needed-focal |
| Mauricio Faria de Oliveira (mfo) wrote | #36 |
This issue was fixed in the openstack/nova 28.0.0.0rc1 release candidate.