Function TestCheckIdleConn

stdlib/sql_test.go:1310–1372

(t *testing.T)

}

func TestCheckIdleConn(t *testing.T) {
	controllerConn, err := sql.Open("pgx", os.Getenv("PGX_TEST_DATABASE"))
	require.NoError(t, err)
	defer closeDB(t, controllerConn)

	skipCockroachDB(t, controllerConn, "Server does not support pg_terminate_backend() (https://github.com/cockroachdb/cockroach/issues/35897)")

	db, err := sql.Open("pgx", os.Getenv("PGX_TEST_DATABASE"))
	require.NoError(t, err)
	defer closeDB(t, db)

	var conns []*sql.Conn
	for range 3 {
		c, err := db.Conn(context.Background())
		require.NoError(t, err)
		conns = append(conns, c)
	}

	require.EqualValues(t, 3, db.Stats().OpenConnections)

	var pids []uint32
	for _, c := range conns {
		err := c.Raw(func(driverConn any) error {
			pids = append(pids, driverConn.(*stdlib.Conn).Conn().PgConn().PID())
			return nil
		})
		require.NoError(t, err)
		err = c.Close()
		require.NoError(t, err)
	}

	// The database/sql connection pool seems to automatically close idle connections to only keep 2 alive.
	// require.EqualValues(t, 3, db.Stats().OpenConnections)

	_, err = controllerConn.ExecContext(context.Background(), `select pg_terminate_backend(n) from unnest($1::int[]) n`, pids)
	require.NoError(t, err)

	// All conns are dead they don't know it and neither does the pool. But because of database/sql automatically closing
	// idle connections we can't be sure how many we should have. require.EqualValues(t, 3, db.Stats().OpenConnections)

	// Wait long enough so the pool will realize it needs to check the connections.
	time.Sleep(time.Second)

	// Pool should try all existing connections and find them dead, then create a new connection which should successfully ping.
	err = db.PingContext(context.Background())
	require.NoError(t, err)

	// The original 3 conns should have been terminated and the a new conn established for the ping.
	require.EqualValues(t, 1, db.Stats().OpenConnections)
	c, err := db.Conn(context.Background())
	require.NoError(t, err)

	var cPID uint32
	err = c.Raw(func(driverConn any) error {
		cPID = driverConn.(*stdlib.Conn).Conn().PgConn().PID()
		return nil
	})
	require.NoError(t, err)