fix(spanner): spanner sessions will be cleaned up from the backend (#…

…6679)

* fix(spanner): spanner sessions will be cleaned up from the backend

* fix test

spanner/client.go

@@ -359,11 +359,6 @@ func (c *Client) BatchReadOnlyTransaction(ctx context.Context, tb TimestampBound
 		sh  *sessionHandle
 		err error
 	)
-	defer func() {
-		if err != nil && sh != nil {
-			s.delete(ctx)
-		}
-	}()
 
 	// Create session.
 	s, err = c.sc.createSession(ctx)

spanner/client_test.go

@@ -3250,7 +3250,8 @@ func TestClient_CloseWithUnresponsiveBackend(t *testing.T) {
 	defer cancel()
 	sp.close(ctx)
 
-	if w, g := context.DeadlineExceeded, ctx.Err(); w != g {
-		t.Fatalf("context error mismatch\nWant: %v\nGot: %v", w, g)
+	// session pool close does not trigger any request to backend
+	if ctx.Err() != nil {
+		t.Fatalf("context error mismatch\nWant: nil\nGot: %v", ctx.Err())
 	}
 }

spanner/session.go

@@ -343,8 +343,6 @@ func (s *session) destroyWithContext(ctx context.Context, isExpire bool) bool {
 	}
 	// Unregister s from healthcheck queue.
 	s.pool.hc.unregister(s)
-	// Remove s from Cloud Spanner service.
-	s.delete(ctx)
 	return true
 }
 

spanner/session_test.go

@@ -417,10 +417,6 @@ func TestTakeFromIdleListChecked(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed to get session: %v", err)
 	}
-	ds := server.TestSpanner.DumpSessions()
-	if g, w := uint64(len(ds)), sp.incStep-1; g != w {
-		t.Fatalf("number of sessions from mock server mismatch\nGot: %v\nWant: %v\n", g, w)
-	}
 	if sh.getID() == wantSid {
 		t.Fatalf("sessionPool.Take still returns the same session %v, want it to create a new one", wantSid)
 	}
@@ -494,10 +490,6 @@ func TestTakeFromIdleWriteListChecked(t *testing.T) {
 	if err != nil {
 		t.Fatalf("failed to get session: %v", err)
 	}
-	ds := server.TestSpanner.DumpSessions()
-	if g, w := uint64(len(ds)), sp.incStep-1; g != w {
-		t.Fatalf("number of sessions from mock server mismatch\nGot: %v\nWant: %v\n", g, w)
-	}
 	if sh.getID() == wantSid {
 		t.Fatalf("sessionPool.Take still returns the same session %v, want it to create a new one", wantSid)
 	}