refactor session management for harvester

[rshewitt]

User Story

In order to reduce waste of db resources, datagov wants to refactor how db sessions are managed in harvester

Acceptance Criteria

[ACs should be clearly demoable/verifiable whenever possible. Try specifying them using BDD.]

• GIVEN the places where db operations occur (e.g. load manager, flask app, harvester, etc...)
  AND a db session is required to perform those operations
  WHEN the refactor happens
  THEN each entity performing db operations manages its own db session and lifecycle
  [AND optionally another verifiable outcome]

Background

[Any helpful contextual notes or links to artifacts/evidence, if needed]

Security Considerations (required)

[Any security concerns that might be implicated in the change. "None" is OK, just be explicit here!]

Sketch

[Notes or a checklist reflecting our understanding of the selected approach]

[SueValente]

Could do a better job of how we are managing sessions. we have bad app code that produces idling transitions...

For load manager used for flask app and harvester.. any entity should have clear boundaries and what they are doing with DB. Not currently designed this way. Need to improve how we end sessions. hanging sessions are not good. Bad for DB. biggest offender was fixed recently but want to be aware of idling.. new relic change will give us more information for the level of importance for this ticket.