Background monitor that periodically polls Postgres for blocked queries and reports the lock chain.

Catches lock contention between async tests as it happens, instead of waiting for the ownership timeout (15-120s).

Configuration

config :sandbox_case,
  sandbox: [
    lock_monitor: true
    # or with options:
    lock_monitor: [interval: 2_000, repo: MyApp.Repo]
  ]

What it reports

When a query is blocked waiting for a lock, the monitor logs:

• The blocked query and how long it's been waiting
• The blocking query and its state
• Both Postgres PIDs for further investigation