This can improve issues with deadlocks where multiple touch calls are triggered in a single update, for example where an exchange touches it's parent enterprise on save, and we do this:
oc_with_lots_of_exchanges.exchanges.each{|ex| ex.clone! }
- Context is used to customize some CSS specifications as sometimes display can be different (depending on the context)
- variant variable was not used: copy/paste error
Without syncing the two threads with a lock, the spec could accidentally
pass even if the code is broken. It was accidentally removed during
refactoring in b0fa1464f.
This (should) considerably improve traces like
https://app.datadoghq.com/apm/trace/917632173599137280?spanID=3163385094622710144&env=production&sort=time&colorBy=service&spanViewType=metadata&graphType=flamegraph&shouldShowLegend=true
by fixing the following 3 N+1s
```
user: root
GET /admin/customers.json?enterprise_id=4
USE eager loading detected
Customer => [:enterprise]
Add to your query: .includes([:enterprise])
Call stack
/usr/src/app/app/serializers/api/admin/customer_with_calculated_balance_serializer.rb:24:in `balance_value'
/usr/src/app/app/serializers/api/admin/customer_with_calculated_balance_serializer.rb:9:in `balance'
/usr/src/app/app/controllers/admin/customers_controller.rb:20:in `block (2 levels) in index'
/usr/src/app/app/controllers/admin/customers_controller.rb:17:in `index'
user: root
GET /admin/customers.json?enterprise_id=4
USE eager loading detected
Spree::Address => [:state]
Add to your query: .includes([:state])
Call stack
/usr/src/app/app/serializers/api/address_serializer.rb:14:in `state_name'
/usr/src/app/app/controllers/admin/customers_controller.rb:20:in `block (2 levels) in index'
/usr/src/app/app/controllers/admin/customers_controller.rb:17:in `index'
user: root
GET /admin/customers.json?enterprise_id=4
USE eager loading detected
Spree::Address => [:country]
Add to your query: .includes([:country])
Call stack
/usr/src/app/app/serializers/api/address_serializer.rb:10:in `country_name'
/usr/src/app/app/controllers/admin/customers_controller.rb:20:in `block (2 levels) in index'
/usr/src/app/app/controllers/admin/customers_controller.rb:17:in `index'
```
This popped up after improving the balances calculation. Now, that it's
fast, it's clear that are more performance problems on that endpoint.
We'll see if there are any left after this.
