with_advisory_lock

# File activerecord/lib/active_record/migration.rb, line 1312
      def with_advisory_lock
        lock_id = generate_migrator_advisory_lock_id
        got_lock = Base.connection.get_advisory_lock(lock_id)
        raise ConcurrentMigrationError unless got_lock
        load_migrated # reload schema_migrations to be sure it wasn't changed by another process before we got the lock
        yield
      ensure
        Base.connection.release_advisory_lock(lock_id) if got_lock
      end