Slow but small response for virtual columns seemingly due to N+1 queries

[jrafanie]

From a customer's DB, a request such as:

/api/vms?expand=resources&attributes=num_cpu,name

is only a 64KB response but takes 1.6 seconds.

joerafaniello@Joes-MBP-2 manageiq % bundle exec miqperf benchmark -ac 5 -d "/api/vms?expand=resources&attributes=num_cpu,name"
D, [2020-07-24T14:03:52.849756 #29451] DEBUG -- : --> logging in...
D, [2020-07-24T14:03:53.124855 #29451] DEBUG -- : --> making GET request: /api/vms?expand=resources&attributes=num_cpu,name
D, [2020-07-24T14:03:54.854853 #29451] DEBUG -- : --> making GET request: /api/vms?expand=resources&attributes=num_cpu,name
D, [2020-07-24T14:03:56.618859 #29451] DEBUG -- : --> making GET request: /api/vms?expand=resources&attributes=num_cpu,name
D, [2020-07-24T14:03:58.366955 #29451] DEBUG -- : --> making GET request: /api/vms?expand=resources&attributes=num_cpu,name
D, [2020-07-24T14:04:00.306892 #29451] DEBUG -- : --> making GET request: /api/vms?expand=resources&attributes=num_cpu,name
joerafaniello@Joes-MBP-2 manageiq % bundle exec miqperf report -l
/api/vms
|   ms | queries | query (ms) | rows |
| ---: |    ---: |       ---: | ---: |
| 1624 |    1117 |      640.8 | 1666 |
| 1650 |    1116 |      653.0 | 1665 |
| 1638 |    1116 |      638.1 | 1665 |
| 1699 |    1116 |      688.8 | 1665 |
| 1681 |    1116 |      637.1 | 1665 |

related to #805

[Fryguy]

https://github.com/ManageIQ/manageiq/blob/cca2bd8e9c8839deff16ff62a2be49558885f8f4/app/models/vm_or_template.rb#L178

Feels like the code is either

• not preloading at all
• not detecting that this delegate goes through hardwares and thus not preloading it
• not supporting a :uses => :hardwares for preloading

[NickLaMuro]

@miq-bot assign @NickLaMuro

[miq-bot]

This issue has been automatically marked as stale because it has not been updated for at least 3 months.

If you can still reproduce this issue on the current release or on master, please reply with all of the information you have about it in order to keep the issue open.

Thank you for all your contributions! More information about the ManageIQ triage process can be found in the triage process documentation.

[miq-bot]

@NickLaMuro 'NickLaMuro' is an invalid assignee, ignoring...