Revert "Fix unknown symbol error during head compaction (#7526)" (#7556)

This reverts commit 30505a202a.

tsdb/head.go

@@ -1692,6 +1692,8 @@ func (h *Head) getOrCreateWithID(id, hash uint64, lset labels.Labels) (*memSerie
 	h.metrics.seriesCreated.Inc()
 	atomic.AddUint64(&h.numSeries, 1)
 
+	h.postings.Add(id, lset)
+
 	h.symMtx.Lock()
 	defer h.symMtx.Unlock()
 
@@ -1707,10 +1709,6 @@ func (h *Head) getOrCreateWithID(id, hash uint64, lset labels.Labels) (*memSerie
 		h.symbols[l.Value] = struct{}{}
 	}
 
-	// Postings should be set after setting the symbols (or after holding
-	// the symbol mtx) to avoid race during compaction of seeing partial symbols.
-	h.postings.Add(id, lset)
-
 	return s, true, nil
 }
 

tsdb/head_test.go

@@ -1875,70 +1875,3 @@ func TestHeadLabelNamesValuesWithMinMaxRange(t *testing.T) {
 		})
 	}
 }
-
-func TestHeadCompactionRace(t *testing.T) {
-	// There are still some races to be fixed. Hence skipping this test
-	// for now to not cause flaky CI failures.
-	t.Skip()
-
-	for i := 0; i < 10; i++ {
-		t.Run(fmt.Sprintf("run %d", i), func(t *testing.T) {
-			tsdbCfg := &Options{
-				RetentionDuration: 100000000,
-				NoLockfile:        true,
-				MinBlockDuration:  1000000,
-				MaxBlockDuration:  1000000,
-			}
-
-			db, closer := openTestDB(t, tsdbCfg, []int64{1000000})
-			t.Cleanup(closer)
-			t.Cleanup(func() {
-				testutil.Ok(t, db.Close())
-			})
-
-			head := db.Head()
-
-			// Get past the init appender phase here.
-			app := head.Appender()
-			_, err := app.Add(labels.Labels{labels.Label{Name: "n", Value: "v"}}, 10, 10)
-			testutil.Ok(t, err)
-			testutil.Ok(t, app.Commit())
-
-			wait := make(chan struct{})
-			var wg sync.WaitGroup
-
-			// Prepare to execute concurrent appends.
-			wg.Add(100)
-			for i := 0; i < 100; i++ {
-				go func(idx int) {
-					defer wg.Done()
-					app := head.Appender()
-					<-wait
-
-					for j := 0; j < 100; j++ {
-						// After compaction this will return out of bound, so this is a best effort append.
-						app.Add(labels.Labels{labels.Label{
-							Name:  fmt.Sprintf("n%d", idx*100+j),
-							Value: fmt.Sprintf("v%d", idx*100+j),
-						}}, 1000, 10)
-					}
-
-					testutil.Ok(t, app.Commit())
-				}(i)
-			}
-
-			// Prepare for head compaction.
-			wg.Add(1)
-			go func() {
-				defer wg.Done()
-				<-wait
-				testutil.Ok(t, db.CompactHead(NewRangeHead(head, 0, 10000000)))
-			}()
-
-			// Run concurrent appends and compaction.
-			close(wait)
-
-			wg.Wait()
-		})
-	}
-}