RSpec Connection Pool Exhaustion – Diagnose cleanup strategy

Diagnosing Intermittent Connection Pool Exhaustion

The goal is to determine whether the observed pool exhaustion during long‑running RSpec suites is caused by the default transactional fixture handling or by the DatabaseCleaner strategy employed. Constraints include the Rails version (≥6 with connection reaping), the presence of background‑job‑like tests that open extra connections, and the configuration of config.after(:suite) for cleanup.

Key uncertainties revolve around whether config.use_transactional_fixtures = true guarantees immediate return of connections to the pool after each test, and how DatabaseCleaner.clean_with(:truncation) interacts with the pool’s state. The interaction of config.after(:suite) cleanup with Rails’ connection reaping also remains unclear.

To resolve these, consider the following questions:

• Does use_transactional_fixtures always return connections to the pool immediately after each test?
• What effect does DatabaseCleaner.clean_with(:truncation) have on the pool’s available connections during after(:suite)?
• In a CI environment, how does the timing of connection reaping influence intermittent exhaustion reports?